Whenever EC2 is included you need to use Auto Scaling to automatically scale the number of
instances which only leaves 2 potential answers. EBS volumes can only be mounted to a single
instance and so data cannot be shared therefore that rules out the other potential answer.
Therefore EC2 with Auto Scaling and an ELB sitting in front is the correct solution
DynamoDB can be used for storing session state for stateless web applications but is not
necessary for the answer