Answer:
The alternative which best describes the purpose and audience for the essay is the following one:
A. to explain how wonderful this place is; someone who has not been there.
Explanation:
If you are writing about your <u>favorite</u> family camping spot, it means you like that place and has good things to say about it. An appropriate audience is someone who has not been there, so they learn about a new place.
<u>Letters C and D must be ruled out for the following reason:</u>
It is a place both you and your family like, so it makes no sense writing it for your parents or siblings, since they are all obviously familiar with the place.
<u>Letter B must re ruled out for the following reason:</u>
It does not make sense to try to persuade the audience not to go there, since you like it (unless you were utterly selfish and did not want to share it with anyone).