What is The mutation caused by the addition of a nucleotide to an already existing gene sequence called? A. deletion B. duplication C. insertion D. Inversion ??

Insertion

Explanation:

An example of this genetic disorder is the trisomy 21

answer; i believe is(b)converging

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.