If father of C’s mother’s brother is the father-in-law of B’s sister’s mother’s daughter-in-law.
Then how is B’s father related to C’s father?

(1) Father-in-law
(2) Brother-in-law
(3) Son-in-law
(4) Uncle
(5) Father

[spoiler]
Father-in-law. Figure this one out yourself ;)[/spoiler]