A man says, “My son’s mother is the only daughter of your father.” How is the man related to the person being spoken to?

Correct — B. Replace each phrase with the person it names.

Rule: "my son's mother" is the speaker's wife.

The man is saying: "My wife is the only daughter of your father."

A woman listener is a daughter of her own father, and as the only daughter she is the one named. His wife is the person he is speaking to, so he is her husband, option (b).

Why the others are wrong

• (a)
  Brother — A brother would be a son of the listener's father. This man married that father's daughter, so he is family by marriage, not by birth.
• (c)
  Son-in-law — Son-in-law is the man's tie to the listener's father, whose daughter he married. The question asks for his tie to the listener.
• (d)
  Son — A son would make his wife the listener's daughter-in-law, a generation below the listener. The statement puts her in the listener's own generation.

Two phrases in this item collapse. "My son's mother" is the speaker's wife, and "the only daughter of your father", said to a woman, loops back to that woman herself.

Substitute both and the sentence becomes "My wife is you", so the relation reads off directly: husband.

The word only does the work. Without it, "a daughter of your father" could be the listener's sister.

Key facts

• A man's son's mother is his wife.
• Said to a woman, "the only daughter of your father" names the woman herself.
• Said to a man, the same phrase names his sister, which would make the speaker his brother-in-law.

Common traps

• Choosing Son-in-law, which is the man's relation to the listener's father, not to the listener.
• Reading "the only daughter of your father" as the listener's sister, then finding no brother-in-law among the options.

No directly related past PYQ was found.