henry's hamburger heaven offers its hamburgers with the following condiments: ketchup, mustard, mayonnaise, tomato, lettuce, pickles, cheese, and onions. a customer can choose one, two, or three meat patties, and any collection of condiments. how many different kinds of hamburgers can be ordered? (a) 24 (b) 256 (c) 768 (d) 40,320 (e) 120,960