A man said, “My mother’s husband's only son is the father of your sister’s brother.” How is the man related to you?

Correct — B. Rule: resolve the speaker's side first, then the listener's.

My mother's husband = my father.
My father's only son = me, since the speaker is a man.

The sentence becomes "I am the father of your sister's brother".

Your sister's brother is you, or your brother. In both cases his father is your father, so the man is your father — option (b).

Why the others are wrong

• (a)
  Uncle — An uncle would be your parent's brother. The speaker is the father of your sister's brother, which makes him your parent, not your parent's sibling.
• (c)
  Grandfather — A grandfather is a parent's father. Your sister's brother is in your own generation, so his father is one generation above you, not two.
• (d)
  Brother — A brother would share your parents. The speaker is the father of your sister's brother, so he stands a full generation above you.

Long chains shrink when you resolve the speaker's side first. "My mother's husband" is my father, and "my father's only son", said by a man, is the speaker himself.

Then resolve the listener's side the same way. Your sister's brother is you, or a brother who shares your parents.

Either reading gives the same father, so the listener's gender never needs to be known.

Key facts

• My mother's husband is my father.
• A man's father's only son is the man himself.
• Your sister's brother is you or your brother, and either way has your father.

Common traps

• Stopping at "my father's only son" and answering Brother.
• Counting "father of your sister's brother" as two generations and choosing Grandfather.

No directly related past PYQ was found.