Answer: C) Plants absorb the nitrogen from the soil and animals can eat the plants.
Heterotrophs, specifically herbivores and omnivores, are animals that eat plants (autotrophs) to get the nutrients they need. Those that eat the plants get the nitrogen from the plant that has absorbed it from the soil. Omnivores and carnivores eat the herbivores to get nitrogen that way. For more more information, take a look at the nitrogen cycle.