Which is correct?

Your firm has uploaded a large amount of aerial image data to S3 In the past, in your onpremises environment, you used a dedicated group of servers to oaten process this data and
used Rabbit MQ -An open source messaging system to get job information to the servers.
Once processed the data would go to tape and be shipped offsite. Your manager told you to
stay with the current design, and leverage AWS archival storage and messaging services to
minimize cost. Which is correct?

A.
Use SQS for passing job messages use Cloud Watch alarms to terminate EC2 worker instances
when they become idle. Once data is processed, change the storage class of the S3 objects to
Reduced Redundancy Storage.

B.
Setup Auto-Scaled workers triggered by queue depth that use spot instances to process
messages in SOS Once data is processed,

C.
Change the storage class of the S3 objects to Reduced Redundancy Storage. Setup Auto-Scaled
workers triggered by queue depth that use spot instances to process messages in SQS Once
data is processed, change the storage class of the S3 objects to Glacier.

D.
Use SNS to pass job messages use Cloud Watch alarms to terminate spot worker instances
when they become idle. Once data is processed, change the storage class of the S3 object to
Glacier.

Explanation:
The question key part to focus on is “and leverage AWS archival storage and messaging
services to minimize cost.”
For that the storage that is the lowest cost in the answers is Glacier, in addition, the
messaging cost is less for SQS then for SNS if they both exceed 1 million transactions which

is free. The only answer that satisfies the above two criteria is answer C. Also, there does not
seem to be an urgency in speed of messaging therefore SQS satisfies that need. SNS being
more real time delivery mechanism.