Step 1: Understanding the Concept:
This question asks for a specific detail about the lawyer's activities during his confinement in Anton Chekhov's story, 'The Bet'.
Step 2: Detailed Explanation:
The story chronicles the lawyer's fifteen-year imprisonment year by year. It details the books he reads and the activities he undertakes to combat his extreme loneliness and boredom.
In the first year, the lawyer is described as suffering terribly from solitude and depression. To cope, he "played the piano and rejected wine and tobacco." The music was a way for him to pass the time and express his emotions.
Step 3: Final Answer:
During the first year of imprisonment, the lawyer played the piano.