Relationship Of X To Y Or Relationship Bet'n X & Y

The relationship of smoking and lung cancer have been firmly established, yet people continue to ignore warnings, jeopardizing their health and that of others.

(A) The relationship of smoking and lung cancer have been firmly established, yet people continue to ignore warnings, jeopardizing their health and that of others.
(B) The relationship of smoking to lung cancer has been firmly established, yet people continue to ignore the warnings, jeopardizing their health and that of others.
(C) The relationship of smoking to lung cancer has been firmly established, yet people continually ignore the warnings which jeopardize their own health and that of others.
(D) The relationship between smoking and lung cancer has been firmly established, yet people continue to ignore warnings, jeopardizing their own health and that of others.
(E) The relationship of smoking with lung cancer has been firmly established, with people continuing to ignore the warnings and jeopardizing their own health and others.

Please explain the correct answer.

Thanks in advance.