Introducing a boy, Ankit said, 'He is the son of the daughter of my grandfather's son.' How is that boy related to Ankit?

Introduction / Context:
This blood relation question uses a nested description: the son of the daughter of my grandfather's son. You must slowly unpack this chain and then compare the resulting person to Ankit. The question also tests your familiarity with a common exam convention, where my grandfather's son is usually interpreted as my father unless extra information suggests additional sons.

Given Data / Assumptions:
- Reference person: Ankit. - There is a boy being introduced. - The boy is the son of the daughter of Ankit's grandfather's son. - Grandfather refers to Ankit's paternal grandfather in the typical exam setting. - No extra sons of the grandfather are mentioned, so grandfather's son is taken to be Ankit's father.

Concept / Approach:
We decode the relation step by step. First find who my grandfather's son is. Under usual test assumptions, this is Ankit's father. Then find the daughter of that person: she is Ankit's sister. Finally, the boy is the son of that sister. The son of your sister is defined as your nephew. Therefore, the boy is Ankit's nephew, and Ankit is his maternal uncle.

Step-by-Step Solution:
Step 1: Identify my grandfather's son. In standard reasoning for such questions, Ankit's grandfather's son is interpreted as Ankit's father. Step 2: The daughter of Ankit's father is a female child of the father. That can be either Ankit's sister or, if Ankit himself is female, possibly Ankit. The wording introducing a boy through Ankit makes it most natural to treat this daughter as Ankit's sister. Step 3: The boy is the son of that daughter. If the daughter is Ankit's sister, then the boy is the son of Ankit's sister. Step 4: The son of your sister is your nephew. Therefore, the boy is Ankit's nephew. Step 5: The question asks how the boy is related to Ankit, so we say that he is Ankit's nephew.

Verification / Alternative check:
You can draw a three-generation tree: the grandfather at the top, his son (Ankit's father) in the middle, and two children at the bottom level: Ankit and his sister. The sister then has a son. From the sister's viewpoint, the boy is her son. From Ankit's viewpoint, the boy is her sister's son, i.e., nephew. Although theoretically the grandfather could have more than one son, exam questions of this format generally intend the unique straightforward interpretation leading to nephew.

Why Other Options Are Wrong:
- Cousin: A cousin would share grandparents with Ankit but would be a child of Ankit's uncle or aunt, not of his sister. - Brother: A brother would share at least one parent with Ankit. Here, the boy is one generation below Ankit's sister. - Father-in-law: This is a marriage-based relation, not supported by any information in the question. - Uncle: An uncle is a sibling of your parent or the husband of your aunt. The boy is younger and belongs to a lower generation.

Common Pitfalls:
Some students get stuck on the ambiguity of my grandfather's son and start imagining multiple uncles, which leads to multiple possibilities. However, competitive exams usually assume the simplest family structure consistent with the wording, especially when no other children are mentioned. Another pitfall is to stop the chain early and misidentify the daughter as a cousin rather than a sister. Carefully following each phrase all the way from grandfather down to the boy avoids such errors.

Final Answer:
The boy introduced by Ankit is his nephew.