Pointing to a girl, a woman says, 'She is the daughter of my mother’s only daughter.’ How is the girl related to the woman?

Correct — A. Resolve the phrase from the inside out.

Rule: a woman's 'mother's only daughter' is the woman herself.

The woman is her mother's daughter. If her mother has just one daughter, it must be her.

So 'the daughter of my mother's only daughter' is the daughter of the woman. The girl is her daughter, option (a).

Why the others are wrong

• (b)
  Daughter-in-law — A daughter-in-law is a son's wife, joined by marriage. The girl is the daughter of the speaker herself, a blood relation.
• (c)
  Cousin — A cousin would be the daughter of the mother's sister, not of the mother's daughter. And the mother's only daughter is the speaker.
• (d)
  Sister — A sister would be 'my mother's daughter'. The stem goes one step further, the daughter of that daughter, which is one generation down.

Relation phrases nest. 'The daughter of my mother's only daughter' is read from the speaker outwards: first find my mother's only daughter, then that person's daughter.

The word only does the work. A woman is always one of her mother's daughters, so if there is just one, it is the speaker, and the phrase collapses to 'my daughter'.

Key facts

• Said by a woman, 'my mother's only daughter' means the woman herself.
• Said by a woman, 'my father's only daughter' also means herself.
• Said by a man, 'my mother's only daughter' means his sister.

Common traps

• Reading 'my mother's only daughter' as the speaker's sister. The speaker is a daughter herself, so the only daughter must be her.
• Stopping at 'my mother's daughter' and dropping the extra 'daughter of' in front.

No directly related past PYQ was found.