Performing a risk assessment of the access rights is the best way to address the concern of conflicting access rights during the integration of two companies. A risk assessment will help to identify and prioritize the threats and vulnerabilities that affect the access rights of both companies, as well as the potential impact and likelihood of information exposure. A risk assessment will also provide a basis for selecting and evaluating the controls to mitigate the risks. According to NIST, a risk assessment is an essential component of risk management and should be performed before implementing any security controls1. The other options are not the best ways to address the concern of conflicting access rights during the integration of two companies, but rather possible subsequent actions based on the risk assessment. Reviewing access rights as the acquisition integration occurs may be too late or too slow to prevent information exposure. Escalating concerns for conflicting access rights to management may not be effective without evidence or recommendations from a risk assessment. Implementing consistent access control standards may not be feasible or desirable for different systems or business units. References: 1: NIST SP 800-30 Rev. 1 Guide for Conducting Risk Assessments 2: M&A integration strategy is crucial for deal success but remains difficult: PwC 3: The 10 steps to successful M&A integration | Bain & Company : Cracking the code to successful post-merger integration

Identification and valuation of assets provides the basis for risk management efforts as it relates to the criticality and sensitivity of assets. Management support is always important, but is not relevant when determining the proportionality of risk management efforts. ALE calculations are only valid if assets have first been identified and appropriately valued. Motives, means and opportunities should already be factored in as a part of a risk assessment.

Explanation
Cost-benefit analysis results are the best way to support the business case for an increase in the information security budget because they help to demonstrate the value and return on investment of the proposed security initiatives or projects. A cost-benefit analysis is a method of comparing the costs and benefits of different alternatives or options, taking into account both quantitative and qualitative factors. A cost-benefit analysis helps to justify the need and feasibility of the security budget, as well as to prioritize the security spending based on the expected outcomes and impacts. Therefore, cost-benefit analysis results are the correct answer.
References:
* https://www.cisa.gov/resources-tools/resources/business-case-security
* https://www.cisa.gov/resources-tools/resources/isc-best-practices-making-business-case-security
* https://risk3sixty.com/2020/09/21/how-to-build-a-business-case-for-security-initiatives-part-4/

The best way to ensure that information security concerns are considered during the procurement of SaaS solutions is to integrate information security risk assessments into the procurement process. This will allow the organization to identify and evaluate the potential security risks and impacts of using a SaaS provider, and to select the most appropriate solution based on the risk appetite and tolerance of the organization. Information security risk assessments should be conducted at the early stages of the procurement process, before selecting a vendor or signing a contract, and should be updated periodically throughout the contract lifecycle.
Providing regular information security training to the procurement team (B) is a good practice, but it may not be sufficient to address the specific security issues and challenges of SaaS solutions. The procurement team may not have the expertise or the authority to conduct information security risk assessments or to negotiate security requirements with the vendors.
Inviting IT members into regular procurement team meetings to influence best practice is also a good practice, but it may not be effective if the IT members are not involved in the actual procurement process or decision making. The IT members may not have the opportunity or the influence to conduct information security risk assessments or to ensure that security concerns are adequately addressed in the procurement contracts.
Enforcing the right to audit in procurement contracts with SaaS vendors (D) is an important control, but it is not the most effective way to ensure that information security concerns are considered during the procurement process. The right to audit is a post-contractual measure that allows the organization to verify the security controls and compliance of the SaaS provider, but it does not prevent or mitigate the security risks that may arise from using a SaaS solution. The right to audit should be complemented by information security risk assessments and other security requirements in the procurement contracts.
Reference = CISM Review Manual (Digital Version), Chapter 3: Information Security Program Development and Management, Section: Information Security Program Management, Subsection: Procurement and Vendor Management, Page 141-1421