Final answer:
The correct answer is C. on the verge, which means Martin is very close to experiencing a nervous breakdown.
Step-by-step explanation:
The correct answer is C. on the verge. This phrase means that Martin is very close to experiencing a nervous breakdown. It implies that his mental state is precarious and he could easily reach a breaking point. For example, if Martin is constantly under a lot of stress and exhibiting symptoms such as anxiety, depression, and difficulty coping with everyday tasks, he may be on the verge of a nervous breakdown.
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