Question

the president pro tempore fills in for what figure in congress when they are absent?
the vice president
the speaker of the house
the senate majority leader

Explanation:

In the U.S. Congress, the vice president is the president of the Senate but may not always be present. The president pro tempore of the Senate is the official who presides over the Senate in the vice president's absence. The Speaker of the House is the leader of the House of Representatives (a separate chamber), and the Senate majority leader is a leadership position in the Senate but not the one the president pro tempore fills in for. So the president pro tempore fills in for the vice president.

Answer:

A. the vice president