You run a SIP-based telephony application that uses Amazon EC2 for its web tier and uses MySQL on Amazon RDS as its database. The application stores only the authentication profile data for its existing users in the database and therefore is read-intensive. Your monitoring system shows that your web instances and the database have high CPU utilization.
Which of the following steps should you take in order to ensure the continual availability of your application? (Choose two.)

A. Use a CloudFront RTMP download distribution with the application tier as the origin for the distribution.
B. Set up an Auto Scaling group for the application tier and a policy that scales based on the Amazon EC2 CloudWatch CPU utilization metric.
C. Vertically scale up the Amazon EC2 instances manually.
D. Set up an Auto Scaling group for the application tier and a policy that scales based on the Amazon RDS CloudWatch CPU utilization metric.
E. Switch to General Purpose (SSD) Storage from Provisioned IOPS Storage (PIOPS) for the Amazon RDS database.
F. Use multiple Amazon RDS read replicas.