【正确答案】 B

【答案解析】[听力原文]
   Public schools in Washington D. C. provide students with musical instruments for free. When something goes wrong with an instrument, Charles does the repairs. He has worked there for almost 20 years. This year alone, he has fixed 250 instruments. He approaches his work with a passion. For him, it's important that students have a joyful experience with music. Charles is a musician and music lover, so learning to do repairs comes naturally.
   In addition to fixing instruments, he also goes to schools to instruct teachers and students on how to make minor repairs on their own.
   He believes if children start early and stay involved with music, it will enrich other areas of their lives. "I see that in other kids. I see it in myself. I have seen it hundreds of times and it works." he says. "They learn teamwork. They learn patience and respect."
   But he has concerns about the future of music in the electronic age. "This instant age has taken away from the sit-down, the patience. Learning to play instrument takes patience, diligence, and time."
   Being able to enjoy music on the job is one of the benefits of the job. Charles agrees his best reward is the students' performances.
   What's the job of Charles at school?