Final answer:
Mr. Darcy's reasons for being glad about Elizabeth and Jane's departure are complex, involving his emerging feelings for Elizabeth and his concern over Mr. Bingley's attachment to Jane.
Step-by-step explanation:
The question refers to the character Mr. Darcy in Jane Austen's novel 'Pride and Prejudice.' None of the provided options explicitly state why Mr. Darcy is glad Elizabeth and Jane are going home. However, inferring from the novel, one could assume that Mr. Darcy's reasons are more nuanced. By the time Jane and Elizabeth are to leave, Mr. Darcy has started to realize his deep feelings for Elizabeth, although he has not yet come to terms with them due to his pride and his disapproval of her family's lower social status.
The presence of Jane and Elizabeth at Netherfield has thrown Mr. Bingley into confusion regarding his feelings for Jane, prompting Mr. Darcy to influence Mr. Bingley to leave Netherfield in the hope of severing the connection. Mr. Darcy's relief might therefore be attributed to his complex feelings of attraction towards Elizabeth and his concern for his friend's best interests, which in his view means separating him from Jane.