A bad egg means a dishonest or unreliable person. 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 bad egg can refer to a dishonest or unreliable person.
• Story example: A writer may use A bad egg when describing a dishonest or unreliable person.
• Exam example: When a sentence contains A bad egg, choose the meaning “a dishonest or unreliable person.”