Answer: option D is correct.
Explanation:
Fitness in an individual is also called Darwinian fitness. Note that fitness in individual should not be confused with physical fitness which deal with the physical training for staying healthy. The individual fitness is related to the propagation of gene which in turn increase population.
Option A in the question is about physical fitness, so it is not correct, obviously, B and C Options are not correct too. Fitness here, is the genetic definition which defines fitness as the capacity of a genotype to be propagated into the offsprings.
