Which of the following is a Cabinet-level position?

The Secretary of Education is indeed a Cabinet-level position because it is part of the President's Cabinet, which is a group of the most senior appointed officers in the executive branch of the federal government. These individuals are responsible for leading their respective departments and advising the President on relevant policy matters. The Secretary of Education oversees federal education policy and programs, including federal student aid, national education initiatives, and the enforcement of education laws.

The other roles mentioned do not belong to the Cabinet. The Senate Majority Leader is a leadership role within the Senate responsible for managing their party's legislative agenda but does not have a role in the executive branch. The Ambassador to the UN represents the U.S. at the United Nations and is a significant diplomatic position, but still falls outside the Cabinet designated roles. The Chief of Staff serves as an advisor and manager within the White House, coordinating activities among various departments and advising the President, but is not technically part of the Cabinet itself.