Only variations that confer an advantage to an individual organism will survive in a population.

solution:
No, many of the times the variations are not advantageous to an individual organism but they still survive in a population, e.g., take the case of free ear lobe and attached ear lobe. Most of the other variations not only give survival advantage to an individual but also contribute to genetic drift. Thus we can say that most of the variations lead to better adaptation of an organism to the changing environment. In this way, it gives survival advantage to that organism and will also survive in the coming population.