At the end of one's tether means unable to deal with a difficult situation any longer. 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 the end of one's tether can refer to a situation involving unable to deal with a difficult situation any longer.
• Story example: A writer may use At the end of one's tether when describing a situation involving unable to deal with a difficult situation any longer.
• Exam example: When a sentence contains At the end of one's tether, choose the meaning “unable to deal with a difficult situation any longer.”