K is the brother of N and X. Y is the mother of N and Z is the father of K. Which of the following statements is not definitely true?

Explanation:-

K is the brother of N and X. So, Y, who is the mother of N and Z, who is the father of K, will be mother and father of N, K and X of whom K is a male. Thus,K is the son of Y and Z, and Y is the wife of Z. But, N is either brother or sister of X.