A good writer cannot work well without a plot
Explanation:
a verb form found in many languages that functions as a noun or is used with auxiliary verbs, and that names the action or state without specifying the subject, as French venir “to come,” Latin esse “to be,” fuisse “to have been.”
You want a genitive form here; and the genitive form of "park" is "park's" - so the correct option is b.
it would also be possible to create a composite noun: park gate