Consider the Question and two Statements given below :
Question : Is Z brother of X?
Statement-1 : X is a brother of Y and Y is a brother of Z.
Statement-2 : X, Y and Z are siblings.
Which one of the following is correct in respect of the Question and the Statements?

Correct Option: Statement-2 alone is sufficient to answer the Question

We need to determine if Z is the brother of X based on the given statements. Statement-1: X is a brother of Y and Y is a brother of Z. This establishes a chain of brothers: X is male (brother of Y), Y is male (brother of Z). Therefore, Z is a sibling of X and Y. Since Y is a brother of Z, Z must be either a brother or sister of X and Y (depending on Z's gender, which is not explicitly stated in Statement-1 as Z's gender is relative to Y). Thus, Statement-1 alone is not sufficient to confirm if Z is a brother (could be a sister). Statement-2: X, Y, and Z are siblings. This tells us they are brothers/sisters, but does not specify their individual genders or whether Z is male (a brother). Combining Statement-1 and Statement-2: Statement-1 gives the brother relationship chain, but Z's gender remains ambiguous (Z could be female). Therefore, even with both statements combined, we cannot conclusively prove Z is a brother. Both statements together are not sufficient. Option D is correct.