Answer: An area of a desert can support a population of 320 cactus plants.
Explanation:
The carrying capacity of an ecosystem can be define as the maximum number of individuals of the population of the species that an ecosystem can support on the basis of availability of resources such as water, food, habitat and other resources. When the population of a species in an ecosystem exceeds the carrying capacity of an ecosystem then population will decline as the ecosystem will not support increase in such growth.
According to the above information, An area of a desert can support a population of 320 cactus plants is the correct option.