Introducing a girl, Ankit says, 'She is the sister of the son of my mother's sister.' How is the girl related to Ankit?

Introduction / Context:
This question deals with maternal relatives and cousin relationships. Ankit introduces a girl through the phrase sister of the son of my mother's sister. You must follow the chain from Ankit's mother to her sister, then to that sister's children, and then determine how the girl is related to Ankit. The focus is on recognising the children of one's aunt as cousins.

Given Data / Assumptions:
- Reference person: Ankit. - Ankit's mother has a sister (Ankit's maternal aunt). - This maternal aunt has a son. - The girl introduced is the sister of that son. - So the girl and the aunt's son are both children of Ankit's maternal aunt.

Concept / Approach:
My mother's sister is my maternal aunt. Her son is my cousin (male). The girl is the sister of this cousin and is also the daughter of my maternal aunt. Children of your aunt are your cousins. Therefore, the girl is Ankit's cousin. It is important not to confuse this with a niece or sister, which would require a different set of parents.

Step-by-Step Solution:
Step 1: Identify my mother's sister as Ankit's maternal aunt. Step 2: The son of Ankit's maternal aunt is Ankit's cousin (male), because he is the child of Ankit's aunt. Step 3: The girl mentioned is the sister of that son. Thus she is also a child of Ankit's maternal aunt. Step 4: All children of an aunt (or uncle) are cousins to you. Therefore, the girl is also Ankit's cousin. Step 5: The question asks for the girl's relationship to Ankit. So the correct answer is cousin.

Verification / Alternative check:
Draw the family tree: at the top, put Ankit's maternal grandparents. Their children include Ankit's mother and her sister. From the sister branch, draw two children: the son and the girl. From Ankit's mother branch, draw Ankit. Ankit and both children of the maternal aunt share the same grandparents but have different parents, making them all first cousins. This picture leaves no doubt that the correct relationship is cousin.

Why Other Options Are Wrong:
- Niece: A niece would be the daughter of Ankit's sibling, not the daughter of his maternal aunt. - Daughter: The girl would need to have Ankit as a father, which is not suggested anywhere. - Sister: A sister shares parents with you; the girl has a different mother (Ankit's aunt). - Aunt: An aunt is a sibling of a parent or the wife of an uncle, which describes Ankit's mother's sister, not her children.

Common Pitfalls:
Candidates sometimes see my mother's sister and jump to calling the girl an aunt without finishing the chain my mother's sister's son's sister. Another pitfall is confusing children of aunts and uncles with nieces and nephews. The direction matters: nieces and nephews are children of your siblings; cousins are children of your aunts and uncles. Keeping this direction straight ensures you identify the girl as a cousin.

Final Answer:
The girl introduced by Ankit is his cousin.