Which Ought to Be More Fundamental, the Hypothesis or the Explanandum

Multiple Choice

Which ought to be more fundamental, the hypothesis or the explanandum?

A) The hypothesis when the explanation provides a cause, but the explanandum when it provides a reason.
B) The hypothesis when the explanation provides a reason, but the explanandum when it provides a cause.
C) The two should be equally fundamental.
D) Always the explanandum.
E) Always the hypothesis.