Let's think step by step! Of the below sentences, which one does *not* make sense?
Options:
- Sentence A: "He talked to her using a book shelf"
- Sentence B: "He talked to her using a mobile phone"

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
A book shelf is not a means of communication. The answer: Sentence A.