The testing team created Aurora Read Replica for an RDS MySQL database to evaluate the performance behavior of an Aurora instance under production loads. After completing the evaluation, the team is unable to delete this read replica instance. What is the cause and solution to this problem?

Answer options:

A.Read Replicas must be deleted using CLI with –enable-delete flag.
B.Deletion protection is enabled on the RDS MySQL master database.Disable deletion protection.
C.It is impossible to delete an active read replica instance.Turn off the read replica instance in order to delete it.
D.It is impossible to delete the last instance of a read replica DB cluster.It must be promoted to a standalone DB cluster.

Answer: D
Option A is incorrect because you do not need to use CLI to delete read replicas.
Option B is incorrect because delete protection on the source database does not affect deletion protection on read replicas.
Option C is incorrect because you do not need to shut down a read replica to delete it.
Option D is CORRECT because the read replica cluster must be promoted to a standalone database cluster before it can be deleted.
Reference:
https://aws.amazon.com/premiumsupport/knowledge-center/rds-error-delete-aurora-cluster/