The president pro tempore of the Senate:
A. is the longest-serving member from the majority party.
B. also serves as the chamber’s majority leader.
C. is the most powerful party leader.
D. appoints members of the Rules Committee.
well, then A?
Yes, A. It is not required in the Constitution (it could be any Senator), but it has been custom to choose the most senior member of the majority party since the 1890s, and always since 1949.
thank you! very appreciate your help