In Paragraph 4, how does Kennedy respond to those who believe communism is a positive system?

He expands on the idea by explaining how communism will replace democracy as the system of the future.

He invites these people to witness firsthand the many ways that West Berlin has suffered because of communism.

He highlights the weaknesses of communism by contrasting it with democracy.

He Invites these people to come to West Berlin themselves to see the progress made there due to democracy.