If P is the maternal uncle of Q, how is Q related to P’s sister?

Correct — A. Rule: a maternal uncle is the mother's brother.

P is Q's maternal uncle, so P is the brother of Q's mother.

The key reads P's sister as a sister of P other than Q's mother. She is then Q's mother's sister, Q's maternal aunt.

Q is the child of her sister, so Q is her niece or nephew. Q's gender is not given, so the relation is Niece/Nephew, option (a).

Why the others are wrong

• (b)
  Cousin — A cousin is in Q's own generation, such as P's children. P's sister is one generation above Q, so Q cannot be her cousin.
• (c)
  Son — Son assumes Q is male, and the stem never states Q's gender. It also takes P's sister to be Q's own mother, while the key reads her as Q's aunt.
• (d)
  Cannot be determined — The key treats the relation as fixed: with P's sister read as Q's maternal aunt, Q is her niece or nephew. The note on this card sets out the other reading.

Maternal means on the mother's side. A maternal uncle is the mother's brother, and a maternal aunt is the mother's sister.

So P and Q's mother are siblings, and any sister of P is either Q's mother or Q's aunt.

To an aunt, her sister's child is a niece (a girl) or a nephew (a boy). The combined option covers both, because the stem does not say whether Q is male or female.

Key facts

• A maternal uncle is the mother's brother.
• A sister's child is a niece or a nephew.
• Q's mother is herself one of P's sisters.

Common traps

• Answering Son when the stem never states Q's gender.
• Choosing Cousin, which is Q's relation to P's children, not to P's sister.

No directly related past PYQ was found.