Occurs naturally between organisms living in an environment with limited resources.
a. competition
b. symbioses
c. logistic
d. exponential

The correct answer is A. Competition

Explanation:

In biology, competition refers to a struggle or fight between different species or organisms to obtain a certain source (water, food, shelter) and therefore survive. Competition is a natural factor that helps to preserved balance in the ecosystem but mainly occurs as the resources are limited, for example, two or more species fed on the same type of plant and there are only a few of these plants available, which led to competition to feed and also influences the surviving rate. Thus, it is competition the one that occurs naturally between organisms in an environment with limited resources.

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.