In an ecosystem, there are two color varieties within a species of toads: brown and green. Over 50 years, the proportion of the population that is green increases from 20% to 50%. Which statement is the most likely to explain this change?
a-Pollution caused a decrease in the proportion of brown toads.
b-The environment changed such that green toads can blend into their surrounding better.
c-The environment changed such that toads can jump higher into the trees to survive better.
d-A disease caused a decrease in the proportion of brown toads