What does Hans Rosling mean when he says that he is neither a pessimist nor an optimist, but rather a possibilist? (This is regarding human overpopulation)

A  No answer text provided.

B  He points out the low standards of living of the developing world and sees no way the developed world would care enough to help them achieve a higher standard of living.

C  He points out what we have achieved in certain countries regarding population growth rate and applies it to what can be achieved in others if certain steps are followed.

D  He points to the declining birthrate of the developed world and is confident that the developing world would inevitably improve their standard of living and also have lowered birthrates.