Question

how has the internet revolutionized political campaigns?
it has drastically reduced the need for traditional forms of advertising.
it has increased foreign participation in elections.
it has increased competition between candidates.
it has enabled immediate communication between candidates and supporters.

Explanation:

The internet allows candidates to directly and instantly communicate with supporters via social media, email, etc. Traditional advertising still exists, foreign participation in elections isn't a direct result of the internet in terms of campaigns, and while it may affect competition, the most distinct change is the immediate communication aspect.

Answer:

It has enabled immediate communication between candidates and supporters.