Final answer:
Proofreading and feedback occur in the Reviewing stage of message development to ensure the document is error-free and the message is clear.
Step-by-step explanation:
Proofreading and request for feedback should take place during the Reviewing stage of routine message development. The correct answer to the question is A) Reviewing. During this phase, a detailed examination of the document for errors and the effectiveness of the message is conducted. Feedback is sought to ensure clarity, coherence, and correctness, aiming to refine the message to its best possible form. This is a critical step after the initial draft and before finalization, where one can apply edits and consider critiques from peers.