The correct option is B Individual genes denote the fitness of the gene pool.
Natural selection operates deciding which organism lives and which ones die. Even though individual genes denote the ‘fitness’ of an organism, natural selection always operates at the population level. It is the ‘fitness’ of the gene pool that helps in the survival of the species, individual genes that are lost are insignificant. It is when the ‘gene pool’ is not ‘fit’, that the species will go extinct.