What has been the relationship trend between negative campaign tone and voter turnout in the last 50 years?

ABoth negative campaigns and voter turnout have continually decreased but it is unclear whether they are related.

BAs negative ads have steadily decreased, voter turnout has steadily increased, indicating they have a direct relationship.

CNegative campaigns have steadily increased and it is possible that it increased voter turnout but the evidence is not strong.

DThe increase in negative campaigning matches to a proportional decrease in voter turnout, showing a strong relationship.