Which individual serves as the Secretary of Defense?

The honorable Lloyd Austin serves as the Secretary of Defense, making this choice the correct answer. In the context of the U.S. government, the Secretary of Defense is a senior official who heads the Department of Defense and is responsible for coordinating and supervising all agencies and functions related to national security and the armed forces. Lloyd Austin, who took office in January 2021, has a distinguished military background, having achieved the rank of four-star general in the U.S. Army, which provides him with significant experience in defense and military matters.

The other individuals listed do not hold the office of Secretary of Defense. Captain Uwing, Commander McDermott, and LCDR Urban are fictional or rank-based titles that might not align with the current officeholder in the real-world context of U.S. defense leadership. Their ranks may indicate positions within the Navy, but they do not carry the authority or responsibility that comes with the role of Secretary of Defense.