Answer – D
The AWS Documentation mentions the following.
Proposed solution: an in-memory cache based on Amazon ElastiCache
Because the issue involves latency to the backend database, we propose an in-memory cache based on Amazon ElastiCache to reduce network latency and offload the database pressure. This solution dramatically reduces the data retrieval latency. It also scales request volume considerably because Amazon ElastiCache can deliver extremely high request rates, measured at over 20 million per second. The following diagram shows the proposed architecture.
Option A is incorrect since normally CloudFront distribution is placed in front of the front tier of the application.
Option B is incorrect since this is used for fault-tolerant scenarios for the database.
Option C is incorrect since this is used for queuing messages.
For more information on reducing latency’s for hybrid architectures, please refer to the below URL-
https://aws.amazon.com/blogs/database/latency-reduction-of-hybrid-architectures-with-amazon-elasticache/