A user is comparing purchase options for an application that runs on Amazon EC2 and Amazon RDS. The application cannot sustain any interruption. The application...

A user is comparing purchase options for an application that runs on Amazon EC2 and Amazon RDS. The application cannot sustain any interruption. The application experiences a predictable amount of usage, including some seasonal spikes that last only a few weeks at a time. It is not possible to modify the application.
Which purchase option meets these requirements MOST cost-effectively?