A. He bit off people's jaws: This option is not the answer because it takes the expression "jawing away" too literally. In this context, "jawing away" is an informal phrase that means talking or chatting continuously, not physically biting off people's jaws.

B. He was always chewing in the class: This option is incorrect because it misinterprets the meaning of "jawing away." The phrase refers to talking or chatting, not chewing.

C. He was always making trouble for the class: This option is not the answer because while "jawing away" might imply being talkative, it doesn't necessarily mean causing trouble. It's more about continuous talking or chatter.

D. He talked continuously in the class.
- This option is correct because it accurately captures the meaning of "jawing away" in this context. The sentence indicates that the new boy talked a lot in class, causing the class to become tired of it. So, option D is the best explanation for the information conveyed in the sentence.