Cast light on means help explain or clarify something. 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: Cast light on can refer to a situation involving help explain or clarify something.
• Story example: A writer may use Cast light on when describing a situation involving help explain or clarify something.
• Exam example: When a sentence contains Cast light on, choose the meaning “help explain or clarify something.”