The correct answer is D.)Voting can be time consuming.
The term "cost" refers to the idea that if you are completing one action, than you are missing the chance to use that time for something else. In this case, waiting a long time to vote is considered a cost because you are using that time to vote instead of completing another task that you need to do.
All of the other option choices represent positive effects that voting has on individuals and do not mention the time it takes to vote.