Where is the story so we know what characters we are talking about
The answer is: C. tragicomedy.
A tragicomedy is a play or novel which contains essential features of both tragedy and comedy. As a consequence, the author could write about amusing and comic aspects of a distant country, as well as about events that have been disastrous and have caused great suffering.
The correct answer to you're question is:
B. Studying Mathematics.
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Explanation:
They lived together for a many years and speak to each other like strangers
