The geographic isolation of a population from other members of the species and the subsequent evolution of reproductive barriers between it and the parent species describes speciation

The correct answer is - allopatric speciation.

Explanation:

The isolation of two populations of the same species from one another due to the geographic changes this type of speciation or isolation known as allopatric speciation.

Speciation is the slow process in which the preexisting population of one species evolved to new species. Allopatric speciation, also known as vicariant speciation or geographic speciation,

Thus, the correct answer is -  allopatric speciation.

it's diluted or concentrated

in a diluted solution, you can add a lot more solute but in concentrated only a little more can be added

i think the answer is a.keratin is the pigment responsible for skin color.