Which soil horizon, also known as the zone of accumulation, is enriched in clay, iron oxides, silica, carbonate, and other materials?
A) A Horizon
B) B Horizon
C) C Horizon
D) O Horizon
E E Horizon

a- multicellular

b-eukaryotic

c-no cell wall

d-heterotrophic

e-autotrophic

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.