The correct answer is D: 'Deploy read replicas with equivalent compute and storage resources as the source database.' Creating read replicas in Amazon RDS MySQL allows you to offload read traffic from the primary database, thus improving performance. By configuring the read replicas with the same compute and storage resources as the source database, you ensure that the read performance is comparable to that of the primary database, which is essential for maintaining application performance. Options A and B, relating to Multi-AZ deployments, do not effectively separate read and write traffic, and option C suggests using smaller read replicas, which might not handle the read load effectively.