The duplicity theory of vision holds that a single receptor system cannot produce both high sensitivity and high resolution. What does this theory explain

1 and 6 for apex

answer; /// the correct )

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.

your answer is going to be physical weathering