Pointing to a man, Seema said, 'His mother is the only daughter of my mother's father.' How is the man related to Seema?

Correct — C. Shrink the phrase one step at a time, starting from Seema.

Rule: the only daughter of my mother's father is my mother.

Seema's mother's father = Seema's maternal grandfather
His daughters include Seema's mother, and 'only' says she is the one
So the man's mother is Seema's mother

A man whose mother is Seema's mother is her brother, option (c).

Why the others are wrong

• (a)
  Cousin — A cousin would need his mother to be Seema's aunt. The stem makes her the only daughter of Seema's maternal grandfather, and that is Seema's mother.
• (b)
  Nephew — A nephew would need his mother to be Seema's sister, a granddaughter of that grandfather. The stem makes his mother the grandfather's own daughter.
• (d)
  Son — Son would make Seema the man's mother, and so the daughter of her own mother's father. But her mother's father is her grandfather, and his only daughter is Seema's mother, not Seema.

Long relation phrases get shorter when you replace one compound at a time. 'My mother's father' is Seema's maternal grandfather. His daughters are Seema's mother and any sisters she has.

The word only closes that list: the grandfather has one daughter, so she is Seema's mother. The man shares Seema's mother, which makes him her brother.

Key facts

• My mother's father is my maternal grandfather.
• The only daughter of my mother's father is my mother.
• A man whose mother is my mother is my brother.

Common traps

• Ignoring 'only' and reading the daughter as an aunt, which leads to Cousin.
• Reading 'my mother's ... daughter' as Seema herself, which gives Son. The daughter is the grandfather's, a generation above Seema.

No directly related past PYQ was found.