Choosing an appropriate sample size depends on all of the above factors.
For example, if we want a sample with a high level of confidence, for a population that is very diverse (high variability), and we want the sample to have a very low margin of error, we would need a large sample, in order to make the sample as close as possible to the population as a whole.
Explanation: Mutualism is an ecological relationship between individuals of different species in which everyone involved benefits. It may be mandatory or not.