And an ecosystem there are two color varieties with a species of toes, brown and green over 50 years of proportion of population that is green increases from 20% to 50% which statement is most likely to explain this change

One possible explanation for the increase in the proportion of green toes in the population over 50 years could be natural selection. If the environment in which the population lives provides a better advantage or camouflage for green toes compared to brown toes, individuals with green toes may have a higher chance of survival and reproduction. Over time, this could lead to an increase in the proportion of green toes in the population.