Which of the following factors would have the least effect on the carrying capacity of an ecosystem?
a the total number of organisms
b. the available water supply
c. the available food supply
d. competitive exclusion

d. competitive exclusion

Explanation:

The amount of individuals of a given species that the resources of an environment can support is called the carrying capacity. The density of a population is often less than its carrying capacity when it is limited by predators. If predators are withdrawn, the population may increase to the point of carrying capacity or beyond so that crucial resources are insufficient and the population collapses.

Competitive exclusion has little effect on the carrying capacity of an ecosystem, because if two species are using a common food source, which has little source, the growth of one may deprive the other of its food source. Under some conditions the fastest growing species causes the other population to die and prevents the environment from reaching the limit of carrying capacity.

b. the carbon cycle ensures living things have a source of hydrogen