Correct Answer & Explanation
Option A
Let's break down the statement:
• "My grandfather" refers to the woman's paternal or maternal grandfather.
• "The only son of my grandfather" means the woman's father (if paternal grandfather) or her mother's brother (if maternal grandfather, but usually 'only son' implies the direct lineage).
• Given the context of 'only son of my grandfather', it implies the woman's father.
• "His brother's father" refers to the man's father.
• So, the man's father is the woman's father.
• This means the man and the woman are siblings.
• Therefore, the woman is the man's sister.