Final answer:
Animals that feed on both plants and animals are called omnivores. This category includes species such as humans, bears, and crows, which vary their diets based on availability or life stages.
Step-by-step explanation:
Animals that feed on both plant and animal tissues are referred to as C) omnivores. Omnivores are animals that consume a variety of food sources, including both plants and animals. This generalist dietary strategy allows them to adapt to a wide range of environments and food availability. Examples of omnivores include humans, pigs, brown bears, and some bird species like gulls and crows. Additionally, some species may vary their diet depending on seasonal availability or life stages, such as grizzly bears that shift from eating primarily fish to consuming berries depending on the time of year.