Final answer:
The title 'Sweet Difficult Sounds' does not correspond to a widely recognized book; therefore, the main characters cannot be determined. The correct answer is D. None of the above.
Step-by-step explanation:
The question asks about the main characters' names in the book Sweet Difficult Sounds. Unfortunately, there might be a confusion or mistake regarding the title of the book as there seems to be no widely recognized book by this name. If the student is referring to a lesser-known book, self-published work, or a new release that has not yet gained wide recognition, additional context or clarification would be needed to provide an accurate answer. Therefore, based on the information given and widely recognized literary works, the correct answer would be D. None of the above, since Sweet Difficult Sounds is not a known title with characters that can be identified.