Final answer:
The combination of genes during sexual reproduction most likely results in variation within a population due to processes like genetic recombination, fertilization, and meiosis, which promote genetic diversity. The correct answer is c) Variation within a population.
Step-by-step explanation:
The combination of genes during sexual reproduction is most likely to result in Variation within a population. This is because sexual reproduction involves mechanisms such as genetic recombination, fertilization, and meiosis that increase genetic diversity.
This diversity can provide a population with a greater ability to adapt to changing environments, thereby enhancing its survival over time. Specifically, sexual reproduction often leads to varying phenotypes among offspring, increasing the genetic variability within a population. It should be noted that sexual reproduction does not produce many identical offspring; that is more characteristic of asexual reproduction, which can be successful in stable environments but does not promote much genetic variation.