Catch someone red-handed means catch someone while doing something wrong. 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: Catch someone red-handed can refer to a situation involving catch someone while doing something wrong.
• Story example: A writer may use Catch someone red-handed when describing a situation involving catch someone while doing something wrong.
• Exam example: When a sentence contains Catch someone red-handed, choose the meaning “catch someone while doing something wrong.”