Correct answer - "RDS" : Amazon Relational Database Service (Amazon RDS) makes it easy to set up,
operate, and scale a relational database in the cloud. Amazon RDS supports the most demanding
database applications. You can choose between two SSD-backed storage options: one optimized for
high-performance OLTP applications, and the other for cost-effective general-purpose use.
Incorrect:
"DynamoDB" - RDS uses expensive joins which DynamoDB does not making DynamoDB a better choice for
scaling by storing complex hierarchical data within a single item
"Redshift" - RDS is your best choice here but Amazon Redshift provides an excellent scale-out
option as your data and query complexity grows
"ElastiCache" - You can use ElastiCache in combination with RDS. This would be a good option for
slow performing database queries in RDS that need to be cached for your application users