Final answer:
TV advertising is the most expensive form of advertising, but the Internet and social media are becoming increasingly important.
Step-by-step explanation:
The most expensive form of advertising is TV advertising.
According to eMarketer.com, TV advertising has traditionally been one of the most expensive forms of advertising. However, with recent technological developments, the cost-effectiveness of TV advertising has decreased compared to the Internet and social media campaigns. It is expected that TV advertising will continue to play a major role in conducting political campaigns, but the Internet and social media will also have a significant impact.