At one's leisure means when one has free time. This answer is correct because the expression has a fixed figurative meaning in English. In an SSC idiom question, students should match the whole phrase with its accepted meaning rather than translate each word separately.

• Classroom example: At one's leisure can refer to a situation involving when one has free time.
• Story example: A writer may use At one's leisure when describing a situation involving when one has free time.
• Exam example: When a sentence contains At one's leisure, choose the meaning “when one has free time.”