Which of the following best explains what makes allocation decisions necessary ?

Allocation decisions are necessary due to the existence of scarcity.

This is one of the main principles of the economic science. Resources are scarce so it is crucial the manner in which the society decides who uses each of them. These decisions are transferred to all individuals that compose a society who, adopting different roles, have to make consumer or business decisions regarded the limited supply of resources they have access too. Time is considered one of those resources.

In order to make allocation decisions, is essential to take into account the opportunity cost, which is the cost of rejecting the alternatives when deciding to use a certain option.

This is the right way to cite that reference:

Goodpaster, K. E., Nash, I. I., & De Bettignies, H. (2006). Business ethics: Policies and persons (3rd ed.). Boston, MA: McGraw-Hill/Irwin