Unaffiliated voters may, if they wish, choose to vote for a party's candidates if that party
agrees to allow "cross-over voting." The California Republican Party and the California
Democratic Party have agreed to let unaffiliated voters vote for their candidates.
-League of Women Voters of Califomia
Based on this excerpt, what is the main purpose of crossover voting?
a. to prevent a third party from complicating an election
b. to allow state officials to monitor election sites for irregularities
c. to increase citizen participation during primary elections
d. to require political parties to spend more money on campaigns