The sentence that can be added to this paragraph to develop the characters through reflection is:
D. Jonah felt nervous as he imagined waking into a class full of strangers
This sentence reveals how Jonah feels. Also, it lets the reader have some more insight about the character through reflection. The sentence reflects that Jonah is not comfortable around strangers and that is why he is nervous. On the other hand, option A lets the reader know who Mr. Dolce is but it does not develop in any way the characters through reflection. Options B and C express facts that the reader already knows; they do not develop the characters through reflection.