Change one's tune means change one's opinion or attitude. 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: Change one's tune can refer to a situation involving change one's opinion or attitude.
• Story example: A writer may use Change one's tune when describing a situation involving change one's opinion or attitude.
• Exam example: When a sentence contains Change one's tune, choose the meaning “change one's opinion or attitude.”