Answer:
The correct answer is: the Senate majority leader sets the floor agenda and supervises the committee chairmen.
Explanation:
In the US Senate, the majority leader is elected by the U.S. Congresspeople in the political party with the largest number of seats in the House, and thus he or she becomes the spokesperson of said party.
Most of the time, the majority leader is either Democrat or Republican.
Since the majority leader represents the majority of the Senate, he or she gets to schedule the day and the subject the Senate will discuss on.
