What is a fixed allele? O A. An allele that mutates with each generation
B. An allele that is found on many genes
C. An allele present in all members of a population
ОО
D. An allele that formed by adaptive radiation

youre right there are

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.