As a last resort means only when all other choices have failed. 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: As a last resort can refer to a situation involving only when all other choices have failed.
• Story example: A writer may use As a last resort when describing a situation involving only when all other choices have failed.
• Exam example: When a sentence contains As a last resort, choose the meaning “only when all other choices have failed.”