A Company's Website Is Using an Amazon RDS MySQL Multi-AZ

A company's website is using an Amazon RDS MySQL Multi-AZ DB instance for its transactional data storage. There are other internal systems that query this DB instance to fetch data for internal batch processing. The RDS DB instance slows down significantly the internal systems fetch data. This impacts the website's read and write performance, and the users experience slow response times. Which solution will improve the website's performance?

A) Use an RDS PostgreSQL DB instance instead of a MySQL database.
B) Use Amazon ElastiCache to cache the query responses for the website.
C) Add an additional Availability Zone to the current RDS MySQL Multi.AZ DB instance.
D) Add a read replica to the RDS DB instance and configure the internal systems to query the read replica.