Correct answer: B). The fittest organisms are selected for.
The theory of Natural selection is given by Charles Darwin, according to it, the natural selection is the process in which the organism that is more suited are selected by the natural selection and they are most likely to survive and reproduce in order to pass these traits to the next generation.
The organism with the highest survival and reproduction will be those whose genes best represented in the next generation. Natural selection occurs to cause evolution and select the fittest.