Final answer:
In Darwinian theory, individuals within a population that have the greatest reproductive success exhibit the greatest fitness for evolutionary success because they pass on advantageous traits to future generations.
Step-by-step explanation:
According to Darwinian theory, the answer to which factor exhibits the greatest fitness for evolutionary success is E) the individuals within a population that have the greatest reproductive success. This is because Darwinian fitness is directly related to an organism's ability to survive and produce offspring that will also survive and reproduce. Adaptations that enhance reproductive potential are crucial for Darwinian fitness, and as environments change, those individuals with characteristics best suited to the changes are more likely to survive and pass their advantageous traits to subsequent generations.