B. the people who set up Pyramid schemes are able to fool honest people.
Feedback he fact that the Pyramid scheme is set up by a con artist suggests that the honest people who invest have been fooled. Choices a and b are contradicted in the passage. The paragraph says that the Pyramid scheme originated in the 1920s, but does not say it had its heyday then; thus, choice d is incorrect. Choice e is a fact, but it is not mentioned in the passage.