Answer:
b. an effort to talk long enough to prevent a vote on a bill.
Step-by-step explanation:
A filibuster is a political process which consists of debating over a proposed piece of legislation in a way that purposely delays or prevents having to make a decision on it. This usually takes place in a Parliament or Congress, as these are generally the bodies of government that deliberate on legislation. This form of obstruction in a legislature is a powerful political device.