Explanation
The AWS Documentation mentions
In Elastic Beanstalk, you can create a load-balancing, autoscaling environment or a single-instance environment. The type of environment that you require depends on the application that you deploy.
When you go onto the Configuration for your environment, you will be able to see the Environment type from there

Explanation
The AWS Documentation mentions the following on AWS Pipeline
The following components of AWS Data Pipeline work together to manage your data:
* A pipeline definition specifies the business logic of your data management.
* A pipeline schedules and runs tasks. You upload your pipeline definition to the pipeline, and then activate the pipeline. You can edit the pipeline definition for a running pipeline and activate the pipeline again for it to take effect. You can deactivate the pipeline, modify a data source, and then activate the pipeline again. When you are finished with your pipeline, you can delete it.
* Task Runner polls for tasks and then performs those tasks. For example. Task Runner could copy log files to Amazon S3 and launch Amazon EMR clusters. Task Runner is installed and runs automatically on resources created by your pipeline definitions. You can write a custom task runner application, or you can use the Task Runner application that is provided by AWS Data Pipeline.
For more information on AWS Pipeline, please visit the link:
* http://docs.aws.amazon.com/datapipeline/latest/DeveloperGuide/what-is-datapi peline.html

https://github.com/aws/Trusted-Advisor-Tools/tree/master/LowUtilizationEC2Instances

Explanation
Since the number of calls is just a few times a week, there are many open source systems such as Jenkins which can be used as CI based systems.
Jenkins can be used as an extensible automation server, Jenkins can be used as a simple CI server or turned into the continuous delivery hub for any project.
For more information on the Jenkins CI tool please refer to the below link:
* https://jenkins.io/
Option A and C are partially correct, but since you just have 5 deployments per week, having separate instances which consume costs is not required. Option B is partially correct, but again having a separate system such as Opswork for such a low number of deployments is not required.

Elastic Beanstalk worker environments support Amazon Simple Queue Service (SQS) dead letter queues.
A dead letter queue is a queue where other (source) queues can send messages that for some reason
could not be successfully processed. A primary benefit of using a dead letter queue is the ability to
sideline and isolate the unsuccessfully processed messages. You can then analyze any messages sent
to the dead letter queue to try to determine why they were not successfully processed.
Reference:
http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/using-features-managing-env-tiers.html#worker-d
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