Hello ,

Jaise Apne Idhar poochha Hai Ki ,aapka Jo mama hai uska beta aapka brother Honge .

aur brother ka beta aapko to chacha hi bulayega. so, the answer hai B. CHACHA.

SAYED ME APKA HELP KAR SAKA.

Answer hain B. Chacha.

(MAMA is your mother's brother)
So, suppose, Your brother's Mama is A. Mama's or (A's) son is B (who is brother of your brother) and C is the son of B.
So your brother will be Uncle to C.
Hence, Chacha (uncle)