Which chamber of congress has staggered terms?

The United States Congress has two chambers: the House of Representatives (ften referred to simply as "the House") and the Senate. The House does not have staggered terms: every single member of the House of Representatives is elected to a two-year term, and all of the seats in the House are voted on at the same time.    

The Senate, however, does have staggered terms. Senators are elected to six-year terms, but only a third of the seats in the Senate are up for election in a given election year. Federal election years are held on even years (2010, 2012, 2014, etc.), and on any given year only about a third of Senators will face reelection. This framers of the Constitution designed the Senate this way to make sure there was some continuity from one Congress to the next.

The answer is closed primary.

Ibelieve that the answer is (a).