Why Is Gridlock, or the Lack of Any Major Legislation

Why is gridlock, or the lack of any major legislation passing through a government split between the two major political parties, so prevalent in the modern American government?

A) Gridlock is not a major issue with any branch of the US government, judicial, executive, or legislative .
B) Gridlock is so prevalent because the two major political parties have no significant legislation to pass .
C) Gridlock in the US government is caused by the two major political parties having near equal influence, with each having the ability to block legislation from the other party .
D) Gridlock in the US government is prevalent because the two major political parties are unsure which legislation would most benefit the American people .
E) Gridlock has been the result of a fracturing of the two major political parties, preventing either party from having enough power in Congress to pass legislation .