In the Context of Elections, Which of the Following Is

In the context of elections, which of the following is true of the ground game?

A) It refers to the use of advertising to promote the views of a presidential candidate.
B) It is a colloquial term used to refer to a candidate's opponents.
C) It involves making public appearances a month before a general election.
D) It is the attempt to learn damaging information about an opponent in a political campaign.
E) It emphasizes the importance of making human contact with target voters.