In this task, you're given a context passage, followed by a question that needs to be answered. Based on the paragraph, you must write unambiguous answers to the questions and your answer must refer to a specific phrase from the paragraph. If multiple answers seem to exist, write the answer that is the most plausible.
Q: Suddenly , the helper guy changed the movie to another one .. with the first one remaining incomplete . A man who was very interested in the movie protested and asked the helper why he did so .. the helpers reply ... thrs a carbon deposit on the CD ... so it wo nt work . The man sat down without saying another word and i was smiling inside . Doctors are considered to be extremely intelligent people and i agree to that ... my father being one ... .but their intelligence fails when they work with something electronic .
Question: Why did the helper guy change the movie to another one ?
A:
There was a carbon deposit on the CD