How is the number of organisms with a mutated gene affected over generations?

The correct choice highlights the principle of natural selection and how certain mutations can confer advantages that increase an organism's chances of survival and reproduction. When a mutated gene provides a benefit, such as increased resistance to disease or improved ability to find food, individuals carrying that mutation are more likely to survive and produce offspring. Consequently, the frequency of the mutated gene can increase in the population over generations, as those advantageous traits are passed on to succeeding generations.

In contrast, other options suggest that the number of organisms with the mutated gene remains constant, decreases, or is eliminated by environmental factors. While environmental influences can affect gene frequency, if a mutation is beneficial, it is more likely to persist and grow in prevalence within the population, aligning with the principles of evolution and natural selection.