As a matter of course means as a normal or expected thing. 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: As a matter of course can refer to a situation involving as a normal or expected thing.
• Story example: A writer may use As a matter of course when describing a situation involving as a normal or expected thing.
• Exam example: When a sentence contains As a matter of course, choose the meaning “as a normal or expected thing.”