The fourth one that looks like an M. This is because it describes changes in population genetics in which extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups.
Claim: Whales evolved from land mammals to water mammals.
Evidence: The first whales evolved over 50 million years. One of the first whales, such as Pakicetus, were land animals with long skulls and carnivorous teeth, much like many adaptable land mammals back then and today.