The correct answer is: A. Always upright.
A pyramid of energy is a graphical representation of the energy flow through an ecosystem. It is always upright because energy is always lost as it moves up the food chain. This is because some of the energy is used for the organism’s metabolic processes, some is lost as heat, and some is excreted as waste.
Option B is incorrect because the pyramid of energy can never be inverted. This is because energy is always lost as it moves up the food chain. If the pyramid of energy were inverted, it would mean that more energy is available at the top of the food chain than at the bottom. This is not possible, because energy is always lost as it moves up the food chain.
Option C is incorrect because the pyramid of energy can never be inverted. This is because energy is always lost as it moves up the food chain. If the pyramid of energy were inverted, it would mean that more energy is available at the top of the food chain than at the bottom. This is not possible, because energy is always lost as it moves up the food chain.
Option D is incorrect because the pyramid of energy is always upright. This is because energy is always lost as it moves up the food chain.