Answer:
The correct answer is option b. "Helpful variations accumulate among surviving members of the species".
Step-by-step explanation:
Natural selection is the most accepted theory of evolution, described by Charles Darwin in 1859. This theory explains that by the survival of the fittest, the helpful variations accumulate among surviving members of the species. The variations or mutations that are not helpful for the species are lost by predators and environmental factors, while the helpful variations remain in the surviving members, which leads to the species evolving to have improved characteristics.