Answer:All inhabitants residing of a distinct species in a place or region that is defined is called population. The inhabitants of a population share the same characteristics.
Explanation:All cacti in the same area can be considered as the population.
The population can be explained as:
The population have the same characteristic sharing organisms living in a defined area together. They share the characters like population density and size, birth and death rate.
All plants, all species and the lizards and ants will not make a population as they consist of different species and does not have a distinct or only a particular group of species.
Therefore, option b. all cacti will make population.