Final answer:
Herbivores that feed on plants, known as primary consumers, are located on the second trophic level of an energy pyramid, right above the primary producers who occupy the first level. The correct option is b.
Step-by-step explanation:
Primary consumers, which are herbivores that feed on plants, are found on the second trophic level of an energy pyramid. Each step of the food chain in the energy pyramid is called a trophic level. At the first trophic level are the primary producers, which are photosynthetic organisms such as plants or phytoplankton. Following them on the second trophic level are the primary consumers, which are the herbivores that consume the producers. Then come the secondary consumers that typically feed on the primary consumers, and so on.
Moreover, it is important to note that higher-level consumers such as tertiary consumers eat secondary consumers and this pattern extends up to the apex consumers at the top of the food chain.