What conclusion can best be drawn from the information in the table?
a. more states offered same-day registration than states that did not.
b. states with same-day registration had a higher voter turnout than states without same-day registration.
c. more voters cast ballots in 2008 than in 2012, no matter what their state’s registration policy.
d. voter turnout was much the same in states with and without same-day registration.