For many in the united states, it seems logical and natural to place barack obama in the racial category of "black," even in the face of clear evidence that he is of mixed biological heritage. this is an example of

I believe the answer is: racial common sense

racial common sense refers to the process of categorizing an individual toward a certainn racial group based on the characteristic that predominantly held by members of the racial group.
Other example would be when we're categorizing someone as asian because that person have yellowish skin and narrow eyes.

The correct option here is:

c. food , water, and shelter

Explanation:

According to Mr. Freamon, creatures within an ecosystem  compete for various sorts of resources that are with  limited availability to them and this competition in a way decides their hierarchy and their place in the food chain.

This is mainly determined on the three main parts:

food

water

shelter

Water is aplenty near rivers but a major resource in arid areas similarly food availability and shelter have always been major issues.