If M is brother of N, B is brother of N and M is brother of D, then wh

If M is brother of N, B is brother of N and M is brother of D, then which one of the following statements is definitely true ?

N is brother of B
N is brother of M
N is brother of D
M is brother of B
This question was previously asked in
UPSC CAPF – 2019
The relationships given are: M is brother of N, B is brother of N, and M is brother of D.
From “M is brother of N” and “B is brother of N”, we know that M and B are siblings of N.
From “M is brother of D”, we know that M is a sibling of D.
Since M is a sibling of N and also a sibling of D, N and D must also be siblings of M. Thus, M, N, B, and D are all siblings.
M and B are explicitly stated as brothers, meaning they are male. The genders of N and D are not explicitly stated.
Let’s examine the options:
A) N is brother of B: Not necessarily true, N could be female (sister).
B) N is brother of M: Not necessarily true, N could be female (sister).
C) N is brother of D: Not necessarily true, N could be female (sister).
D) M is brother of B: Since M and B are both siblings of N (M is brother of N, B is brother of N), they must be siblings of each other. M is stated as male (“brother”), so M is indeed the brother of B. This statement is definitely true.
In blood relation problems, accurately mapping the relationships and genders (where specified) is crucial. Identifying common relatives helps establish connections between individuals not directly linked in the initial statements. The term “sibling” implies being a brother or sister. “Brother” implies male gender.
Using diagrams or symbols (e.g., square for male, circle for female, vertical line for parent-child, horizontal line for siblings) can help visualize the relationships and avoid confusion, especially in more complex problems. When a person’s gender is not specified (e.g., just “sibling”), their gender cannot be assumed.