It is the tropical plants. The text asks about population which is defined as the total number of an object or an entity. In scientific researches, samples are drawn from population to explore either qualitatively or quantitatively a phenomenon. Moreover, biologists study plants as subjects in this study.
Mean is average
so we have 4 numbers
sum them then divide by 4
(32+31+37+44)=144
divide by 4
144/4=36
answer is C
The least common denominator is 1.