Pointing towards a boy, Meera said, "He is the son of the only son of my grandfather." How is that boy related to Meera?

Introduction / Context:
This question is almost symmetric to earlier ones: it uses the phrase the only son of my grandfather and then the son of that person. You must figure out how this boy is placed relative to Meera. The word only is important, as it ensures that the grandfather has exactly one son, strongly suggesting that this son is Meera's father in standard exam logic.

Given Data / Assumptions:
- Speaker: Meera. - Her grandfather has only one son. - The boy is the son of that only son. - We assume that the only son of the grandfather is Meera's father. - Meera is one of the children of this only son.

Concept / Approach:
If Meera's grandfather has a single son, that son is logically her father rather than an uncle, because there is no other male child for the grandfather. The boy in question is another child of this same father, so he is in the same generation as Meera and shares the same parent. Therefore, the relationship between Meera and the boy is that of siblings. Given the boy is male, he is Meera's brother and she is his sister.

Step-by-Step Solution:
Step 1: Recognise that my grandfather's only son refers to Meera's father, since there is exactly one son to carry the line. Step 2: The boy is the son of this only son, so the boy is a son of Meera's father. Step 3: Meera herself is also a child of her father, so both she and the boy share the same father. Step 4: Children of the same father and mother are siblings. With the boy explicitly male, he is Meera's brother. Step 5: Hence, the boy is Meera's brother and Meera is his sister.

Verification / Alternative check:
Draw a simple tree: grandfather at the top, only son below him. The only son is Meera's father. On the next level, place Meera and the boy as the children of this father. In this configuration, both children share the same parent and stand in the same generation, which is precisely a sibling relationship. No other role like cousin or uncle fits the structure.

Why Other Options Are Wrong:
- Cousin: Cousins are children of siblings. Here, both Meera and the boy share the same father, so they are siblings, not cousins. - Uncle: An uncle must be a brother of a parent or the husband of an aunt, not a sibling in the same generation. - Brother-in-law: A brother-in-law is either the brother of a spouse or the husband of a sibling; this is a marriage-based relation, not a direct blood sibling. - Nephew: A nephew is the son of a brother or sister. The boy is not a child of Meera's sibling but of Meera's father.

Common Pitfalls:
Sometimes students incorrectly treat my grandfather's son as an uncle and then assume the boy is a cousin. However, the word only is crucial: if there is only one son, and Meera is a grandchild, that son is her father, not some other relative. Always pay attention to words like only, elder, younger that reduce ambiguity in these questions.

Final Answer:
The boy is Meera's brother.