Answer: C. Bait and switch
Explanation: Bait and switch is a sale tactics which is considered fraudulent and deceptive. In this sale tactics customers are invited through advertisements to come purchase a low price goods, on getting there the goods is unavailable and they are persuaded to buy another of higher price.
William and Marcelo were a victim of "bait and switch* sale tactics, they were lure by the low price "bait" when they got there it was unavailable and were offered another product of higher price "switch".