They get killed ___ the end of the film.

1. at
2. in
3. to
4. on

“At the end” correctly indicates the specific point when the killing occurs—the film’s conclusion. This refers to the temporal location within the narrative. “In the end” would mean ultimately or after everything, which could also work but with slightly different nuance. “At the end” precisely places the event at the film’s final moments. Understanding this distinction helps describe narrative events accurately.