PT 3 S4 Q23

In a new police program, automobile owners in some neighborhoods whose ... ...

If it is concluded from the statements above that automobile theft has been reduced by the program, which one of the following would it be most important to answer in evaluating that conclusion?
(A) Are owners who are cautious enough to join the program taking other special measures to protect their cars against theft?
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Practice Set: "Weaker" Questions, Set 2 - "Evaluation" Subset