According to the ISACA Cloud Auditing Knowledge Certificate Study Guide, the auditor should review the relationship between the cloud service provider and its service provider to help direct and estimate the level of effort and analysis the auditor should apply1. The auditor should understand the nature and scope of the services provided by the service provider, the contractual obligations and service level agreements, the security and compliance requirements, and the monitoring and reporting mechanisms. The auditor should also assess the risks and controls associated with the service provider, and determine if additional audit procedures are needed to obtain sufficient assurance.
The other options are not the best approach for the auditor. Option A is too strict and might not be feasible or necessary, depending on the type and level of services provided by the service provider. Option C is too lax and might overlook significant risks and gaps in the cloud service. Option D is too narrow and might ignore the impact of the service provider on the cloud customer's business context. References:
* ISACA Cloud Auditing Knowledge Certificate Study Guide, page 13-14.