Which of the following is an example of natural selection?

A predator capturing the slowest prey.
Natural selection is the process by which certain heritable traits become more or less common in a population over time as a result of differential reproductive success. In this case, the heritable trait is speed, and the individuals that are slower are less likely to survive and reproduce, while the faster individuals are more likely to escape and pass on their genes to their offspring. Over time, this can lead to an increase in the frequency of genes that code for faster speed in the population, as those individuals with these genes are more likely to survive and pass on their genes to their offspring.