Answer: C. filibustering
Explanation: The term filibuster originated from a Dutch word that translates to "pirate" and is often used to delay or block legislative action, usually in an effort to hold the Senate floor in order to prevent a vote on a bill.
So by definition, filibustering is a tactic (such as giving long, often irrelevant speeches) employed to delay the proceedings of, or the making of a decision by, a legislative body, particularly the United States Senate.