The systematic study of human population is called, demography.
It seems that you have missed the necessary options for us to answer this question, but anyway, here is the answer. <span>If a researcher finds that one drop of perfume diffused through a three-room apartment is the minimum amount of stimuli needed to notice the scent, then this would be a test of one’s SUBLIMINAL STIMULI. Hope this answers your question.</span>
The best answer is B. The river flooded yearly which allowed the fertile sediment on the bottom of the river to flow onto the farmland, keeping it fertile.
B was not an intolerable act
