If You Are Trying to Prove That a Causes B

If you are trying to prove that A causes B, why does it make sense to have your null hypothesis be "A does not cause B"?

A) Data cannot confirm a hypothesis.
B) It is easier to make strong inductive arguments when rejecting a hypothesis.
C) We must allow for B to cause A.
D) Data cannot confirm a hypothesis and it is easier to make strong inductive arguments when rejecting a hypothesis.