1. A main function of the excretory system is to —
A O generate hemoglobin, which is transferred to red blood cells.
B. utilize the kidneys, which filter waste from the blood to produce urine.
С.
make and store calcium in the bones.
D. send chemical signals for response in the body.

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.

answer; nociceptive pain;