Value delivery is the best indicator of the effectiveness of IT governance in an enterprise because it measures how well IT supports the business objectives and creates value for the stakeholders. The other options are important aspects of IT governance, but they are not as comprehensive as value delivery. References := ISACA, CGEIT Review Manual, 7th Edition, Chapter 1: Framework for the Governance of Enterprise IT, Section 1.2: Principles of IT Governance, p. 9.

According to the web search results, a SaaS contract is a legal agreement between a SaaS provider and a customer that defines the terms and conditions of using the SaaS solution, such as the scope, duration, price, service level, data ownership, security, privacy, compliance, etc. The most effective way to reduce the risk associated with the SaaS solution is to include risk-related requirements in the SaaS contract, such as the following12:
The SaaS provider should comply with the relevant laws and regulations that apply to the customer's industry and location, such as GDPR, HIPAA, PCI DSS, etc.
The SaaS provider should implement adequate security measures and controls to protect the customer's data from unauthorized access, modification, disclosure or loss, such as encryption, authentication, authorization, backup, etc.
The SaaS provider should provide regular reports and audits on the security and performance of the SaaS solution, as well as notify the customer of any security incidents or breaches that may affect the customer's data.
The SaaS provider should guarantee a certain level of availability and reliability of the SaaS solution, and specify the remedies or penalties for any service downtime or disruption.
The SaaS provider should allow the customer to access, export, delete or transfer their data at any time, and ensure that the data are erased or returned to the customer upon termination of the contract.
The SaaS provider should indemnify and hold harmless the customer from any claims, damages or liabilities arising from the use of the SaaS solution.
Including risk-related requirements in the SaaS contract will help to clarify the roles and responsibilities of both parties, as well as to establish trust and accountability between them. It will also help to mitigate the potential risks and challenges of using a hosted SaaS solution34, such as data loss, unauthorized access, compliance violations, service outages, vendor lock-in, etc. The other options are not as effective as including risk-related requirements in the SaaS contract, as they do not address the contractual and legal aspects of using a hosted SaaS solution.