Carnivores that feed on other carnivores are
a. tertiary consumers
b. secondary consumers
c. primary consumers
d. producers

a. tertiary consumers

Carnivores are tertiary consumers since they eat the secondary consumers that gallop the producers.
A biological system or also called, a biotic community is composed mainly of living organisms. These organisms can be classified into the main layman categories of animals and plants, majorly. These creatures can be more furthered classified by how they eat and survive. Plants can make their own food through, photosynthesis. Animals eat and are dependent. Can be classified into subtypes as: herbivores, omnivores and carnivores. What makes all of these organisms a biotic community or a biological system is they contain cells, cells are the basic unit and foundation of every living thing.

If you get a map and put the countries a states all together it forms all one piece you can also tell because of the earth quakes