Humans feed on plants and animals and so they are called as
(a)Carnivores
(b)Omnivores
(c)Herbivores
(d)None of the above

Hint: Like human beings there other organisms like crows, chimpanzees, etc. which are capable of eating both plants and animals. This property is an adaptation developed in evolution to overcome food scarcity and improve the choice of food sources.

Complete answer:
Omnivores are those that feed on plants and animals like humans. Omnivores have an efficient digestive system which aids in the digestion of both plant and animal parts. The related enzymes play a major role in breaking down the complex structures into simpler compounds and finally turning it into glucose.

Additional Information: Carnivores: Carnivores are organisms which feed on other animals to find energy sources. They do not make energy through photosynthesis. They do not consume producers but they feed on the primary consumers.
Herbivores: Herbivores are producers who make energy or biomass by the process of photosynthesis. They do not depend on other organisms for creating energy. They form the base of the ecological pyramid.
Decomposers: Decomposers are organisms that feed on dead plants and animals to find nutrition. They are also the major contributors to the formation of humus in the soil.
So the correct answer is omnivores.

Note: -Humans are also known as top predators, as there are no more organisms to which humans are prey. Since they are consumers of other consumers they are called secondary consumers.
-Other than plants, certain algae, and phytoplanktons are also capable of producing energy and biomass by photosynthesis, which makes them producers.
- The humus produced by decomposers is useful for the terrestrial planets to take useful nitrogen and they are also playing an important role in cycling organic components in the environment.