You have the following architecture deployed in AWS.
a) A set of EC2 Instances which sit behind an ELB
b) A database hosted in Amazon RDS
Of late, the performance on the database has been slacking due to a high number of read requests. Which of the following can be added to the architecture to alleviate the performance issue? (Select TWO.)

Answer options:

A.Add read replica to the primary database to offload read traffic.
B.Use ElastiCache in front of the database.
C.Use AWS CloudFront in front of the database.
D.Use Amazon DynamoDB to offload all the reads. Populate the common read items in a separate table.

Correct Answer - A and B
Option A is correct.
AWS says, "Amazon RDS Read Replicas provide enhanced performance and durability for database (DB) instances. This feature makes it easy to elastically scale out beyond the capacity constraints of a single DB instance for read-heavy database workloads. You can create one or more replicas of a given source DB Instance and serve high-volume application read traffic from multiple copies of your data, thereby increasing aggregate read throughput"
Amazon ElastiCache is an in-memory cache that can be used to cache common read requests.
The below diagram shows how caching can be added to an existing architecture:
For more information on database caching, please visit the URL below:
https://aws.amazon.com/caching/database-caching/
Note:
Option C is incorrect because CloudFront is a valuable component of scaling a website, especially for geo-location workloads and queries, more advanced for the given architecture. 
Option D is incorrect because it will have latency and additional changes as well.