The old man was at the end of his tether after hours of waiting.What does the underlined idiom mean?

Explanation

The idiom 'end of his tether' means to reach a point where one can no longer cope or tolerate a situation, often resulting in feelings of frustration or anger. In the context of the sentence, the old man's prolonged waiting has led him to this breaking point. The other options do not accurately reflect this emotional state. 'Very tired but happy' suggests contentment, 'relaxed and calm' implies ease, and 'surprised' indicates an unexpected reaction, none of which align with the frustration indicated by the idiom.