in which sentence is whom used correctly?

whom took those pictures?

whom has the skills to take these pictures?

do you think he is whom took those pictures?

by whom were those pictures taken?

Which best describes the suspense technique of flashback? an image, color, object, or similar is shown early in the film. it later reappears in a pivotal scene or plot point. details of the story outside of the chronological storyline are provided to the audience, often as a memory. illusions of explosions and other events are presented, often using computer-generated imagery to seem realistic. the screenwriter lets the audience know something the main character does not, usually something important to the plot.