What is TRUE about every point along a production possibilities frontier?

A) Both people are maximizing utility.
B) It is impossible to increase production of either good.
C) All allocations are efficient.
D) It includes some unattainable points.

Every point along the production possibilities frontier represents an efficient allocation of resources, meaning that all available resources are being used to produce goods in the most optimal way possible. Therefore, choice C is the correct answer. Choice A is not necessarily true, as people may not be maximizing utility at every point on the frontier. Choice B is also incorrect, as it is possible to increase production of either good by reallocating resources or improving technology. Choice D is partly true, but it is important to note that not all points on the production possibilities frontier are unattainable, only the ones outside of the frontier itself.