Final answer:
Combination A is not efficient because it is not on the production possibilities frontier, which indicates available resources are not being fully utilized for maximum output; thus, it lacks both productive and allocative efficiency.
Step-by-step explanation:
If Ridgeland produces at combination A and that combination is not on the production possibilities frontier (PPF), then it is not efficient. An efficient production point must be on the PPF, which represents all the combinations of goods that can be produced if all resources are used efficiently. If a production combination is inside the PPF, like combination A in this case, this indicates that there are still available resources that could be used to increase output without increasing the input, meaning the production is not productive efficient.
Additionally, allocative efficiency is a concept where resources are distributed in the most effective manner, satisfying societal needs. Allocative efficiency occurs at points along the PPF but requires productive efficiency first. Therefore, since combination A is not on the PPF, it does not achieve allocative efficiency either, as this requires productive efficiency as a pre-requisite.