At a loose end means not knowing what to do or having nothing useful to do. 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 a loose end can refer to a situation involving not knowing what to do or having nothing useful to do.
• Story example: A writer may use At a loose end when describing a situation involving not knowing what to do or having nothing useful to do.
• Exam example: When a sentence contains At a loose end, choose the meaning “not knowing what to do or having nothing useful to do.”