At cross purposes means misunderstanding each other while working toward different aims. 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: At cross purposes can refer to a situation involving misunderstanding each other while working toward different aims.
• Story example: A writer may use At cross purposes when describing a situation involving misunderstanding each other while working toward different aims.
• Exam example: When a sentence contains At cross purposes, choose the meaning “misunderstanding each other while working toward different aims.”