Which position is responsible for advising the President on defense matters?

The position responsible for advising the President on defense matters is the Secretary of Defense. This individual oversees the Department of Defense and is charged with formulating military policies, managing the armed forces, and ensuring national security. The Secretary of Defense plays a crucial role in guiding the President on issues related to military strategy, defense budgets, and active military engagements.

In contrast, the Secretary of Labor focuses on labor laws and workplace safety, the Attorney General is the head of the Department of Justice and oversees legal matters, and the Secretary of State handles foreign affairs and diplomatic relationships. Each of these roles is vital, but they pertain to different areas of government responsibility, thus highlighting why the Secretary of Defense is the correct answer for advising the President specifically on defense matters.