A company is migrating a single-server, on-premises web application to AWS. The company intends to use multiple servers behind an Elastic Load Balancer (ELB) to balance the load, and will also store session data in memory on the web server. The company does not want to lose that session data if a server fails or goes offline, and it wants to minimize user’s downtime.
Where should the company move session data to MOST effectively reduce downtime and make users’ session data more fault tolerant?

A. An Amazon ElastiCache for Redis cluster
B. A second Amazon EBS volume
C. The web server’s primary disk
D. An Amazon EC2 instance dedicated to session data