Answer:
B. Rockwood should put on a Sunday Parkways event because it builds community.
Step-by-step explanation:
The main advantage of Sunday Parkways, which the the author is trying to prove is that it builds the society by providing people a chance to meet and talk to their neighbors and make new friends. So, this main advantage proposed by the author is also the author's main argument.
Option A and C are incorrect because ideas in A and C are supporting ones to the main idea described in option B.
Option D is incorrect because it is not an argument but just a piece of information.