Who is currently the Commander in Chief of the United States?

The Commander in Chief of the United States is the President, who holds the highest authority over the U.S. Armed Forces. As of the date specified, Joe Biden serves as the President and therefore fulfills the role of Commander in Chief. This position entails making crucial decisions regarding national defense, military operations, and ensuring the protection of the nation and its interests.

The other individuals mentioned in the options have important but distinct roles within the U.S. government and military, such as the Secretary of Defense or other high-ranking officials, but they do not have the ultimate authority over military operations like the President does. Thus, recognizing the President as Command in Chief aligns with the established structure of military leadership in the United States.