The reason why why candidates and politicians use the Internet is: they must use the same media that citizens use.
Using the media that citizens use would allow candidates and politicians to know the type of news that are popular among the citizens in order to control public perception toward them. It also provide an easy method for them to communicate directly with the citizens.
The midwest is predominantly grasslands rulling out B and D, which leaves A but i think the time period of the question is when American migrated midwest post Louisiana purchase, not in the modern times of today. so C