A Company Runs a Three-Tier Application in AWS

A company runs a three-tier application in AWS. Users report that the application performance can vary greatly depending on the time of day and functionality being accessed. The application includes the following components: Eight t2.large front-end web servers that serve static content and proxy dynamic content from the application tier. Four t2.large application servers. One db.m4.large Amazon RDS MySQL Multi-AZ DB instance. Operations has determined that the web and application tiers are network constrained. Which of the following should cost effective improve application performance? (Choose two.)

A) Replace web and app tiers with t2.xlarge instances
B) Use AWS Auto Scaling and m4.large instances for the web and application tiers
C) Convert the MySQL RDS instance to a self-managed MySQL cluster on Amazon EC2
D) Create an Amazon CloudFront distribution to cache content
E) Increase the size of the Amazon RDS instance to db.m4.xlarge