Sentence fragments are groups of words that look like a sentence but that they are not. In general, sentence fragments are avoided especially in formal writing. However, authors sometimes decide to use them for different reasons. Writers may change their sentence structure to create certain effects. For example to emphasize an idea, to convey pace, tone and intensity.
The answer is b. because this way you can hear all the characters thoughts and what they are saying. this lets you know how they truly feel versus how they want you to think they feel.
