Explanation
According to the ISACA Cloud Auditing Knowledge Certificate Study Guide, the primary goal of a cloud auditor during the planning phase of a cloud audit is to address audit objectives1. The audit objectives are the specific questions that the audit aims to answer, such as whether the cloud service meets the security, compliance, performance, and availability requirements of the cloud customer. The audit objectives should be aligned with the organization's context, risk appetite, and expectations. The audit objectives should also be clear, measurable, achievable, relevant, and timely.
The other options are not the primary goal of a cloud auditor during the planning phase of a cloud audit.
Option A is a possible activity, but not the main goal of the planning phase. The appropriate tests are determined based on the audit objectives, criteria, and methodology. Option C is a possible constraint, but not the main goal of the planning phase. The audit resources should be allocated based on the audit scope, complexity, and significance. Option D is a possible outcome, but not the main goal of the planning phase.
The sufficient evidence is collected during the execution phase of the audit, based on the audit plan.
References:
ISACA Cloud Auditing Knowledge Certificate Study Guide, page 12-13.

A RACI chart is a tool used to clarify the roles and responsibilities in processes, projects, or operations. In the context of cloud compliance, documenting these responsibilities in a RACI chart ensures that all parties within the enterprise are aware of their specific obligations regarding compliance with laws and regulations.
This helps in creating a clear, organized view of how each part of the organization contributes to overall compliance, facilitating better coordination and accountability.
References = The answer is informed by general best practices in cloud compliance and governance, which recommend the use of RACI charts or similar tools to delineate responsibilities clearly. While I can't reference specific documents from the CCAK or related resources, these practices are widely accepted in the field of cloud security and compliance.

Explanation
The effect of applicable statutory requirements should have priority in planning the scope and objectives of a cloud audit, as they are the mandatory and enforceable rules that govern the cloud service provider and the cloud service customer. Statutory requirements may vary depending on the jurisdiction, industry, or sector of the cloud service provider and the cloud service customer, as well as the type, location, and sensitivity of the data processed or stored in the cloud. Statutory requirements may include laws, regulations, standards, or codes that relate to data protection, privacy, security, compliance, governance, taxation, or liability. The cloud auditor should identify and understand the applicable statutory requirements that affect the cloud service provider and the cloud service customer, and assess whether they are met and adhered to by both parties. The cloud auditor should also verify that the contractual terms and conditions between the cloud service provider and the cloud service customer reflect and comply with the applicable statutory requirements123.
Applicable industry good practices (A) are important for planning the scope and objectives of a cloud audit, but they are not as high priority as applicable statutory requirements. Industry good practices are the recommended or accepted methods or techniques for achieving a desired outcome or result in a specific domain or context. Industry good practices may include frameworks, guidelines, principles, or best practices that are developed by professional bodies, associations, or organizations that have expertise or authority in a certain field or area. Industry good practices may help the cloud service provider and the cloud service customer to improve their performance, quality, efficiency, or effectiveness in delivering or using cloud services. However, industry good practices are not mandatory or enforceable, and they may vary or change over time depending on the evolution of technology or business needs123.
Organizational policies and procedures are important for planning the scope and objectives of a cloud audit, but they are not as high priority as applicable statutory requirements. Organizational policies and procedures are the internal rules and guidelines that define the objectives, expectations, and responsibilities of an organization regarding its operations, activities, processes, or functions. Organizational policies and procedures may include mission statements, vision statements, values statements, strategies, goals, plans, standards, manuals, handbooks, or instructions that are specific to an organization. Organizational policies and procedures may help the organization to align its actions and decisions with its purpose and direction, as well as to ensure consistency and accountability among its members or stakeholders. However, organizational policies and procedures are not mandatory or enforceable outside the organization, and they may differ or conflict among different organizations123.
Applicable corporate standards (D) are important for planning the scope and objectives of a cloud audit, but they are not as high priority as applicable statutory requirements. Corporate standards are the internal rules and guidelines that define the minimum level of quality, performance, reliability, or compatibility that an organization expects from its products, services, processes, or systems. Corporate standards may include specifications, criteria, metrics, indicators, benchmarks, or baselines that are specific to an organization.
Corporate standards may help the organization to measure and evaluate its outputs or outcomes against its objectives or expectations, as well as to identify and address any gaps or issues that may arise. However, corporate standards are not mandatory or enforceable outside the organization, and they may differ or conflict among different organizations123.
Cloud Audits: A Guide for Cloud Service Providers - Cloud Standards ...
Cloud Audits: A Guide for Cloud Service Customers - Cloud Standards ...
Cloud Auditing Knowledge: Preparing for the CCAK Certificate Exam