Bloomberg: Facebook is providing a new option for its more skeptical advertisers.Marketers can now choose to pay Facebook only if their ads have completely passed through a user’s news feed and been seen by a human being. Separately, any advertisers who want to verify video views can get reassurance from a third party, Moat Inc., the social network said in a blog post. Facebook plans eventually to use Moat for other types of news-feed ads and for the social network’s Instagram app.