You run accounting software in the AWS cloud. This software needs to be online continuously during the day every day
of the week, and has a very static requirement for compute resources. You also have other, unrelated batch jobs that
need to run once per day at any time of your choosing. How should you minimize cost?

A.
Purchase a Heavy Utilization Reserved Instance to run the accounting software. Turn it off after hours.
Run the batch jobs with the same instance class, so the Reserved Instance credits are also applied to the batch jobs.

B.
Purchase a Medium Utilization Reserved Instance to run the accounting software. Turn it off after hours.
Run the batch jobs with the same instance class, so the Reserved Instance credits are also applied to the batch jobs.

C.
Purchase a Light Utilization Reserved Instance to run the accounting software. Turn it off after hours.
Run the batch jobs with the same instance class, so the Reserved Instance credits are also applied to the batch jobs.

D.
Purchase a Full Utilization Reserved Instance to run the accounting software. Turn it off after hours.
Run the batch jobs with the same instance class, so the Reserved Instance credits are also applied to the batch jobs.

Explanation:
Because the instance will always be online during the day, in a predictable manner, and there are a sequence of batch
jobs to perform at any time, we should run the batch jobs when the account software is off. We can achieve Heavy
Utilization by alternating these times, so we should purchase the reservation as such, as this represents the lowest cost.
There is no such thing a “Full” level utilization purchases on EC2.
https://d0.awsstatic.com/whitepapers/Cost_Optimization_with_AWS.pdf