A company has multiple AWS accounts that use consolidated billing.

B. Use the Trusted Advisor recommendations from the consolidated billing account to see all RDS instance checks at the same time.

The consolidated billing account has access to all the other AWS accounts that use consolidated billing. Using the Trusted Advisor recommendations from the consolidated billing account will allow the finance team to see all RDS instance checks for all accounts at the same time.

C. Review the Trusted Advisor check for Amazon RDS Reserved Instance Optimization.

The Trusted Advisor check for Amazon RDS Reserved Instance Optimization provides recommendations for purchasing reserved instances to reduce RDS costs. By reviewing this check, the finance team can identify which RDS instances can be converted to reserved instances to save costs.