Once upon a time in a land over the sea, there lived a girl named Samantha. She was a pretty girl with a good heart,
Though her cruel stepmother did everything in her power
to make her miserable, Samantha always hoped she would
one day meet a kind man and live a happy life.
Which best explains why an author would include this passage as part of the
exposition of a story?

The answer is: "A. In order to give background information".

Step-by-step:

What are the author's purpose examples?

An author's cause in speaking might be to instruct, convince, tell, entertain, educate, startle, excite, sadden, enlighten, punish, console, or many, many others. Like authors, audiences have numerous purposes for analyzing, being attentive to, or otherwise appreciating portions of the conversation.

What's a passage instance?

An example of passage is when you move on a ride and someone tells you to be safe in your travels. An instance of passage is when a vehicle moves thru a constrained area with permission. An example of passage is whilst time moves ahead.