In the senate, the presiding officer is the who usually delegates this duty to the president pro tempore.
a. vice-president of the united states of america
b. speaker of the house
c. majority leader
d. minority leader

The correct answer is A. In the Senate, the presiding officer is the Vice-President of the United States, who usually delegates this duty to the president pro tempore.

Explanation:

The vice-president of the United States is the president of the Senate and directs the sessions of this one; however, he is not a senator and his vote does not count, with the exception of cases in which there are ties. Seldom does the vice president act as president of the Senate and, in general, only acts as such in cases where his vote is valid to settle a tie, or during the occasional ceremonies, so the duty of the Senate's presidency usually falls on the president pro tempore, who by tradition is the oldest senator of the party that owns the majority in the Senate, who almost always delegates the task of presiding over a junior senator from his own party.

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