The correct answer is B) people like saving the planet.
Because of the usage of fossil oil and coal extensively in the last few hundred years the Earth and the environment are suffering very badly, this of course affects the humans, their health and life in total. It is obvious that if this trend continues we will make the planet unrecognizable and destroy big portion of it, which will make us suffer or die out as well, so people have been trying to develop renewable energy as much as possible for both the planet's and their own well being, but also are trying to make it as cheep as possible so that it is economically not damaging.