1. A3P means A is the mother of P 2. A4P means A is the brother of P 3. A9P means A is the husband of P 4. A5P means A is the daughter of P Which of the following means that K is the mother-in-law of M?

The correct answer is $\boxed{\text{C. K5J9M3N}}$.

Here is a brief explanation of each option:

• Option $\text{A. M9N3K4J}$ means that M is the husband of N, N is the brother of K, and K is the daughter of J. This does not mean that K is the mother-in-law of M.
• Option $\text{B. M9N5K3J}$ means that M is the husband of N, N is the daughter of K, and K is the brother of J. This does not mean that K is the mother-in-law of M.
• Option $\text{C. K5J9M3N}$ means that K is the mother of J, J is the husband of M, and M is the daughter of N. This means that K is the mother-in-law of M.
• Option $\text{D. K3J9N4M}$ means that K is the brother of J, J is the daughter of N, and M is the husband of K. This does not mean that K is the mother-in-law of M.