In a suburban community in the Southeast, neighborhood security guards ... ...

If it is true that the burglary rate has decreased in this community since the reporting procedure was implemented, then which of the following would be most important to know to make sure the conclusion is valid?
(A) Are residents who report their travel plans to the security office also taking other precautions to protect their homes while they are away?
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Nova Press: Set H - Even More Classification Practice