The correct option is D Primary consumers
The autotrophic organisms make their own food by photosynthesis. Primary consumers feed on producers. Secondary consumers feed on primary consumers. Scavengers feed on dead animals and plants parts while decomposers feed on debris left behind by scavengers and release the nutrients in form of simpler substances back to the atmosphere. Cow eating grass (producers) represent the primary consumer or herbivores. Thus, the correct answer is A.