Answer:
C.
Step-by-step explanation:
First off, the author cannot just change the sound of their voice if it is a book, so clearly, it is not A.
Next, adding exclamation points to a sentence doesn't make it sound uncertain, it sounds exciting, or possibly sarcastic.
Finally, adding phrases like "don't know" and "wonder why" just makes more sense, because this is diction, and it sounds like an uncertain tone.