Final answer:
Option (a) is the best choice for the exposition of the story as it sets the scene, introduces main characters, and provides background information.
Step-by-step explanation:
The question is asking which choice best represents the exposition of a text. The exposition is the part of a story that sets the scene, introduces main characters, and provides background information. In this case, option (a) It's the year 2055, Keith is president, and a wealthy man named Eckels pays to go back in time on a hunting safari best fits the definition of an exposition because it establishes the setting in the future, introduces key characters, and hints at the premise of the story, which is the time-traveling safari.