Hit the sack means go to bed. 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: Hit the sack can refer to a situation involving go to bed.
• Story example: A writer may use Hit the sack when describing a situation involving go to bed.
• Exam example: When a sentence contains Hit the sack, choose the meaning “go to bed.”