the correct answer is A- Reproductive isolation occurred through behavioral isolation
A process of formation of a new species from an existing species is called speciation. New species may formed due to geographical or reproductive barriers which isolates the members of a population of a species to form a new species.
In the given question, speciation in In the leopard frogs occurred due to a particular or specific call given by males to the females. The courtship call lead to reproductive isolation due to change in behavior. Such type of behavioral change will help in recognizing mates of the same species and this will act as a reproductive barrier among the other related species.
I don't think changing seasons can REMOVE CO2 from the air, but I do think instead it could add it to the air. It's a long process that involves several ecosystems and stuff. But, as the climate is getting warmer, ice caps are melting and within these ice caps... there are trapped bubbles of CO2 that are released ( I am not sure if this adds a lot of CO2 to the atmosphere, but I am sure that it does contribute to CO2 concentration).
In relation to your last statement... plant growth would actually reduce CO2 in the air because of the process of photosynthesis. Plants take in CO2 and give out O2 for us to breathe. In turn we conduct cellular respiration in which we take in the O2 and give out the CO2. So, plants are actually one good solution for decreasing CO2 levels.
When a factory is emitting large
amounts of CFCs into the atmosphere, it affects the people in that area by the increase
in the level of ocean water. CFCs dissolve in seawater and because they are not
reactive, they just circulate until it becomes saturated.