I don't know the answer options, but it would probably either be phase of matter or physical change.
The kind of variation that must exist in a population that has a wide range of phenotypes is GENETIC VARIATION.
Genetic variation is started in a population's gene pools which contains all alleles. It is <span>is measured with allele frequency which are calculated by # of specific allele divided by total # of alleles.</span>
Answer: I would go with B. Here’s why: An index fossil is usually easily recognizable, and underwent a wide geographic distribution. What leads me to believe B is the correct answer, is because it’s something that existed “ all over the world”.
