The correct option here is:
c. food , water, and shelter
Step-by-step 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.