Publishers that participate in a display ad network a) get paid each time an advertiser is charged by the ad network for displaying advertisements on the publisher's site. b) have to deal individually with each advertiser running ads on their site. c) need to design and create all ads on their own websites. d) charge the advertisers directly.

The correct option to the following question is an option (a).

Explanation:

Because when the advertisement is published on the publisher's site then any user who visited on his site and if they click on that advertisement then the advertiser gets the credit of that advertisement charge which is paid by the publisher.

That's why this option is correct.

The other options are incorrect because they get charge whenever any visitor clicks on the advertisement.