A business hopes to generate large online sales through posting ads on social networking sites but only wants to pay when an ad actually generates a sale. That firm should use the performance measure of

a negotiated measure, and pay $ $100$ ?to post its ad for two weeks.

cost per like, and pay $ $1$ ?for every unique visitor who likes the advertised product.

cost per thousand, and pay $50$ ?cents for every time an ad loads, up to $ $100$ ?per month.

cost per action, and pay $ $50$ ?for every purchase that originated from an ad on the site.

cost per click, and pay $ $1$ ?for every visitor who clicks on the ad and goes to its website.