Which of the following statements best describes allocative efficiency?

a. As additional increments of resources are added to producing a good or service, the marginal benefit from those additional increments will decline.
b. when it is impossible to produce more of one good (or service) without decreasing the quantity produced of another good (or service)
c. when a country can produce a good at a lower cost in terms of other goods; or, when a country has a lower opportunity cost of production
d. when the mix of goods being produced represents the mix that society most desires

d. when the mix of goods being produced represents the mix that society most desires