What should a solutions architect do to ensure messages are being processed once only?
Use the CreateQueue API call to create a new queue.
Use the AddPermission API call to add appropriate permissions.
Use the ReceiveMessage API call to set an appropriate wait time.
Use the ChangeMessageVisibility API call to increase the visibility timeout.
Explanations:
Creating a new queue does not address the issue of duplicate processing since the original queue remains unchanged.
Adding permissions does not prevent duplicate message processing; it only modifies access rights.
Adjusting the wait time with ReceiveMessage does not impact message processing; it only affects how long the call waits for messages.
Increasing the visibility timeout allows more time for processing the message before it becomes available to other consumers, reducing the chance of duplicate processing.
I compute that the answer is:
Use the ChangeMessageVisibility API call to increase the visibility timeout.