To provide a suitable answer, I would need to know what "part A" refers to. However, based on the information given, here are some interpretations regarding supporting sentences for potential parts A:
- If part A is about the diverse nature of film music composition, A could be the best supporting sentence.
- If part A discusses the collaboration aspects of film composition, B may be the strongest support.
- If part A focuses on historical practices in film composing, then C would be the most relevant.
- If part A addresses the modern methods and paths of becoming a film composer, then D would provide the best support.
Please provide the context or content of part A for a precise response!