Who did the teacher give the new books to?

The correct answer, "us," indicates that the teacher gave the new books to a group that includes the speaker. This choice reflects a plural perspective, suggesting that the speaker is part of a collective who received the books. The use of "us" denotes inclusion and is fitting for situations involving multiple people.

In contrast, "them" refers to a group that is not included in the speaker's perspective, "you" directly addresses another person or group, suggesting that the teacher gave the books to someone else outside the speaker's collective, and "me" implies the focus is solely on the speaker as an individual. Thus, "us" is the most appropriate choice when indicating the shared experience of receiving the books.