Final Answer:
Jane's letter convinces Elizabeth that "accident only could discover to Mr. Bingley her sister's being in town" because Jane's letter did not mention her location. The correct option id B.
Step-by-step explanation:
The critical element in Jane's letter that convinces Elizabeth of the accidental revelation to Mr. Bingley is the absence of information about Jane's location. Since Jane's letter does not specify her whereabouts, Elizabeth infers that the only way Mr. Bingley could learn of Jane's presence in town is through accidental circumstances. This lack of explicit detail in the letter adds a layer of uncertainty, leading Elizabeth to conclude that Mr. Bingley's knowledge of Jane's location would not be intentional but rather a result of chance.
Moreover, Elizabeth's belief in Mr. Bingley's attentiveness and discretion (option C) plays a significant role in her reasoning. If Mr. Bingley were to visit intentionally, Elizabeth assumes that he would have prior knowledge of Jane's whereabouts. However, since Jane's letter is silent on this matter, Elizabeth deduces that any discovery by Mr. Bingley would be accidental, reinforcing her choice of option B.
In summary, the absence of information about Jane's location in the letter aligns with Elizabeth's understanding of Mr. Bingley's behavior, leading her to believe that any revelation to him about Jane's presence in town would be purely accidental.