Given suspected differential bias in a study which of the following statements is TRUE if it is known that the odds of exposure was overestimated in the cases but is a good estimate for the controls (assume the true OR is greater than 1):
a. The OR will be overestimated.
b. The OR will be underestimated.
c. The OR will be closer to the null.
d. If it is differential information bias it is always impossible to say anything about the direction of the OR.