What Was the Effect of More Than a Dozen States

What was the effect of more than a dozen states adopting a requirement that voters show a picture ID at the polls before the 2012 election?

A) It raised the cost of participation for poor and minority voters who are more likely not to possess driver's licenses or passports.
B) It reduced the cost of participation for wealthy White voters who are more likely to have a driver's license or a passport.
C) It did not really have an effect because equal numbers of Republican and Democratic states adopted these new rules so the effects canceled each other out.
D) There was no effect on the cost-benefit calculation for voters because everyone has either a driver's license or a passport.