Lydia told Al, "If you read the problem carefully, then the solution is not difficult."

Which statement is the contrapositive of the above statement?

A.If you read the problem carefully, then the solution is not difficult.

B.If the solution is not difficult, then you have to read the problem carefully.

C.If you do not read the problem carefully, then the solution is difficult.

D. If the solution is difficult, then you have not read the problem carefully.