The term that refers to all the alternatives you give up when you choose one option over the other is "trade-off."
A trade-off occurs when you have to make a decision between two or more choices, where selecting one option means sacrificing the opportunity to choose the others. In the given scenario of choosing between buying a pizza or a bag of candy, making a decision to buy the bag of candy represents a trade-off because you are giving up the opportunity to enjoy the pizza.
By choosing the bag of candy, you are essentially trading off the satisfaction or enjoyment you would have gotten from eating the pizza. Trade-offs are a common concept in economics and decision-making, as individuals and businesses often face situations where they have to weigh the benefits and costs of different options before making a choice.