Can someone help explain this

Which source of law takes

priority in the following situations,and why? Please make sure that you answer all four of the following questions fully and completely. This is not a multiple choice question.

a.A federal statute conflicts with the U.S. Constitution.

b.A federal statute conflicts with a state constitutional provision.

c.A state statute conflicts with the common law of that state.

d.A state constitutional amendment conflicts with the U.S. Constitution.