Step 1: Understanding the Concept:
Blood relation problems are logical puzzles that test your ability to decode complex familial descriptions. The most efficient way to solve these is to break down the sentence into distinct generational steps.
A useful strategy is to read the description backward, starting from the reference person (usually identified by the word "my"). This allows you to build a mental family tree one relationship at a time until the direct connection to the target individual is revealed.
Step 2: Key Formula or Approach:
Deconstruct the descriptive statement from the "inside out":
1. Identify who "my grandfather’s only son" is.
2. Identify who the "daughter" of that person is in relation to the narrator.
Step 3: Detailed Explanation:
Let's decode Ravi’s statement step-by-step:
Step 1: "My grandfather’s only son"
From Ravi’s perspective, his paternal grandfather has only one son. In any standard family structure, the "only son of a grandfather" must be the narrator's own Father.
(Even if we considered the maternal grandfather, the "only son" would be an Uncle, but the standard interpretation in these puzzles points to the direct paternal line unless specified otherwise).
So, the phrase simplifies to "Ravi’s Father."
Step 2: "She is the daughter of [Ravi’s Father]"
Now, substitute the simplified phrase back into the sentence. The description becomes: "She is the daughter of Ravi’s Father."
Someone who is the daughter of your father is someone you share your parents with.
Therefore, that woman must be Ravi’s Sister.
The generational mapping confirms that they are in the same generation and share a direct parent-child link to the same man. This matches option (a) perfectly.
Step 4: Final Answer:
The woman is related to Ravi as his Sister.