He was used to being made fun of.
We know this by him taking this reply in ‘with a sort of humble patience’. This means that he has experienced this kind of teasing - or even bullying before and he is used to it.
C.
"Continues" takes the present tense and also applies that this work is continuous --> ongoing.
The tone of the story "Talk" by Harold Courlander and George Herzog is humorous.
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