Keep one's chin up means remain cheerful in a difficult 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: Keep one's chin up can refer to a situation involving remain cheerful in a difficult time.
• Story example: A writer may use Keep one's chin up when describing a situation involving remain cheerful in a difficult time.
• Exam example: When a sentence contains Keep one's chin up, choose the meaning “remain cheerful in a difficult time.”