Final answer:
Communication with Congress for Congressional action must be accepted and known by the Secretary of Defense, who collaborates closely with the President and is a principal officer in the executive branch overseeing military and defense matters.
Step-by-step explanation:
When considering communication with Congress for Congressional action, it is imperative to know that such communication must have the acceptance and knowledge of a principal officer at a high level in the executive branch. Referring to the information provided and the constitutional role of the President, the correct person who must be aware and possibly initiate such communication would be the Secretary of Defense. The Secretary of Defense is a principal officer in one of the executive departments and is involved in high-level decisions, especially concerning the military and defense aspects. As stated in the references, the President, as Commander in Chief, works closely with the Secretary of Defense and may require their written opinion on matters relating to their duties.
It's also crucial to understand that the Secretary of Defense is a civilian overseer of the military, which emphasizes the constitutional principle of civilian control over the armed forces. This context helps clarify why the Secretary of Defense's knowledge and acceptance are necessary for communications with Congress on defense and military actions.