The policy applies in some states, where there is a federal law and a

The policy applies in some states, where there is a federal law and a provincial law that are each valid and enforceable.

A. is a federal law and a provincial law that are each valid and enforceable -> FLIP the related part: A federal law and a provincial law are there. By flipping, we can see that the compound subject 'a federal law and a provincial law' takes a plural verb 'are'.
B. are a federal law and a provincial law, each of which are valid and enforceable ->The indefinite pronoun each is considered a singular pronoun and requires a singular verb form.
C. a federal law and a provincial law both of which are valid and enforceable -> Try to replace the underlined part with this fragment. A connecting verb between there and this fragmentis missing.
D. are a federal law and a provincial law that are valid or enforceable -> Use of or changes the meaning of the sentence.
E. are a federal law and a provincial law that are each valid and enforceable. Contrast this with A. It uses the correct verb there are. The second verb form that might be confusing that are is also correctly used. Hence, This is the correct answer.

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