A double-edged sword means something that has both advantages and disadvantages. 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: A double-edged sword can refer to a situation involving something that has both advantages and disadvantages.
• Story example: A writer may use A double-edged sword when describing a situation involving something that has both advantages and disadvantages.
• Exam example: When a sentence contains A double-edged sword, choose the meaning “something that has both advantages and disadvantages.”