Solve the quiz….?

Solve this simple blood realtion question,,,

If,

(i) M is brother of N;
(ii) B is brother of N; and
(iii) M is brother of D,

then which of the following statements is definitely true?

a. N is brother of B
b. N is brother of D
c. M is brother of B
d. D is brother of M

 

answer in the comments below, let us c who answers first!