SSC CHSL 19 Mar 2020 Shift 2 Paper

According to the question, Amit's sister's mother's husband is Gagan's daughter's mother's husband's father.
Sister's mother is mother. Daughter's mother is wife.
⇒ Amit's mother's husband is Gagan's wife's husband's father.
Mother's husband is father. Wife's husband is Gagan himself.
$\Rightarrow$ Amit's father is Gagan's father.
∴ Amit is the brother of Gagan.