We are given with a statement given above. The answer is D since there is no erratum involved in the sentence. Children is already plural hence placed after n. Monkey bars and swings are not in the state of owning something so there should not be any apostrophe placed.
Answer:
Ask your parents when they are in a good mood.
Ask to have the sleepover at a convenient time.
Be polite instead of demanding.
Keep the first sleepover simple.
Offer to do something kind in exchange.
Show them that it will be a good opportunity for you to socialize
