The correct answer is A. Cousin.
P’s father Q is B’s paternal uncle. This means that Q is the brother of B’s father. A’s husband M is P’s paternal uncle. This means that M is the brother of P’s father. Therefore, A is the wife of M, who is the brother of Q, who is the father of B. This makes A the cousin of B.
Option B is incorrect because A is not the aunt of B. A’s husband M is the brother of P’s father, but he is not the father of B. Therefore, A is not the aunt of B.
Option C is incorrect because A is not the mother of B. A’s husband M is the brother of P’s father, but he is not the father of B. Therefore, A is not the mother of B.
Option D is incorrect because there is enough data to answer the question. We know that P’s father Q is B’s paternal uncle and that A’s husband M is P’s paternal uncle. This is enough information to determine that A is the cousin of B.
Option E is incorrect because A is related to B. A is the cousin of B.