In the North Pacific Ocean, Two Groups of the Same

Multiple Choice

In the North Pacific Ocean, two groups of the same species of killer whales (Orcinus orca) appear to be forming two different species based on what they eat. One group eats fish and the other eats mammals such as seals. Scientists can tell what they eat based on their teeth, because whales that feed on fish have significantly different wear patterns.
-Which of the following would be the least useful procedure to perform in determining whether or not this speciation has occurred?

A) Compare teeth of whales alive today to teeth of whales in ancient samples.
B) Compare DNA samples from fish eaters and mammal eaters.
C) Compare stomach contents of whales from each of the two populations.
D) Compare body shape of whales from each population.