Answer:
E) Congressional incumbents
Explanation:
PAC money is directed primarily toward congressional incumbents, and this can easily be verified on the web. For example, both Nancy Pelosi, a democrat, and Brian Fritzpatrick, a republican, are among the top incumbents by number of money received from PACs, thus, party affiliation is not as important as it is incumbent status.
This is probably because incumbents are more likely to win elections, whether in the senate, the house, or even, the presidency.
