Changes in society that cause large numbers of people to move up or down the class ladder, which causes one class to increase while others decrease, is called mobility.

classical republicanism, also known as civic humanism, is a form of republicanism  developed in the renaissance inspired by the governmental forms and writings of  classical  antiquity, especially such  classical  writers as aristotle, polybius, and cicero.

it would be d). more resources must be obtained to attain that combination of goods and services