In a Case-Control Study,a Researcher Found No Association Between Exposure

In a case-control study,a researcher found no association between exposure to A and disease B.Later she found out that there was a misclassification when measuring exposure to A,in both cases and controls.What is a potential explanation for the results (no association) of this case-control study?

A) Nondifferential misclassification
B) Differential misclassification
C) Selection bias
D) Confounding
E) Effect-modification