Based on the explanation below, a linear production possibilities curve indicates A. Constant opportunity costs.
A linear production possibility curve (PPC) denotes a situation in which resources are not specialized and can be swapped for one another without incurring additional costs.
As a result, the PPC is a straight line, indicating that opportunity costs remain constant regardless of how far along the curve you move.
Learn more about the production possibilities curve here: https://brainly.com/question/2578952.