Introducing a boy, Sia says, "He is the grandson of my father. I have no siblings." In this situation, how is Sia related to the boy?

Introduction / Context:
This blood relation question involves a simple but important twist: Sia explicitly states that she has no siblings. She also tells us that the boy is the grandson of her father. You need to interpret how someone can be a grandson of Sia's father when Sia is his only child, and from that infer Sia's relation to the boy.

Given Data / Assumptions:

• Sia says, he is the grandson of my father. So the boy is a grandson of Sia's father.
• Sia also says, I have no siblings. So Sia is the only child (only son or daughter) of her father.
• Since Sia is female (from the name and the pronoun she), she is the only daughter of her father.
• A grandson of Sia's father must be a male child of one of Sia's father's children.

Concept / Approach:
If Sia has no siblings, then her father has only one child: Sia herself. For the boy to be a grandson of Sia's father, he must be a child of Sia or a child of some other child of Sia's father. But there is no other child. Therefore, the boy must be Sia's son. Once we recognise that, Sia's relation to the boy is simply mother.

Step-by-Step Solution:
Step 1: Identify Sia's father as F.Step 2: The boy is the grandson of F. So the boy is the son of one of F's children.Step 3: Sia states that she has no siblings, so Sia is the only child of F.Step 4: Therefore, any grandchild of F must be a child of Sia, since there is no other child who could be the parent.Step 5: The boy is a grandson of F and is male, so he is Sia's son.Step 6: Hence, Sia is the boy's mother.

Verification / Alternative check:
Suppose, contrary to the statement, Sia had a brother or sister. Then the boy could be the son of that sibling and Sia would be an aunt. However, Sia clearly says I have no siblings, which rules out that possibility. The only available path from Sia's father to a grandson is via Sia herself. So the boy must be the child of Sia. No other consistent arrangement is possible, making the mother relation certain.

Why Other Options Are Wrong:
Aunt would require the boy to be the child of Sia's sibling, but she has none.Grandmother would require Sia to be one generation above the boy's parent, which is not implied anywhere.Cannot be determined is incorrect because the no siblings condition fully determines the relation.Sister would place both the boy and Sia as children of Sia's father, but that would make the boy a son, not a grandson, of her father.

Common Pitfalls:
Some candidates ignore the crucial line I have no siblings and quickly assume that Sia and the boy are in different branches of the same generation, leading to an aunt guess. Always pay special attention when a puzzle tells you someone has no siblings or only one child; such constraints are deliberately included to force a unique relation.

Final Answer:
Sia is related to the boy as his Mother.