You are planning on deploying an application to the worker role in Elastic Beanstalk. Moreover, this worker application is going to run the periodic tasks. Which of the following is a must-have as part of the deployment?

Answer options:

A.An appspec.yaml file
B.A cron.yaml file
C.A cron.config file
D.An appspec.json file

Answer – B
This is also given in the AWS Documentation.
Create an Application Source Bundle
When you use the AWS Elastic Beanstalk console to deploy a new application or an application version, you`ll need to upload a source bundle. Your source bundle must meet the following requirements.
Consist of a single ZIP file or WAR file (you can include multiple WAR files inside your ZIP file)
Not exceed 512 MB
Not include a parent folder or top-level directory (subdirectories are fine)
If you want to deploy a worker application that processes periodic background tasks, your application source bundle must also include a cron.yaml file. For more information, see Periodic Tasks.
Because of the exact requirement given in the AWS Documentation, all other options are invalid.
For more information on creating an application source bundle for Elastic beanstalk, please refer to the below URL-
https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/applications-sourcebundle.html