Can someone describe natural selection for me?

This is a process whereby the better 'fitted' or adapted varieties of species in populations are selected by environmental pressures. This affects the survival and reproduction of the individuals in the plant/ organism populations in such a way that eventually a variety better adapted to the drier climate dominated the population.

Natural selection is a never-ending process in nature since some environmental factor keeps on changing all he time.

i think the answer is

mass

answer; i believe the correct answer is (sporophyte);