Which of these would generally not be considered part of a watershed?

Which of what? I need more information to decipher that.

answer; /// i believe that the correct answer is (50%);

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.