During a research project, a scientist collects snails from a beach. He finds several snails that have shells of about the same size and shape. However, the shells have very different patterns and colors. How could the scientist best decide whether the snails belong to different species or to the same species?
He could study how the snails develop.
He could examine the snails’ RNA and DNA.
He could classify the snails according to shell color.
He could look for other physical similarities in the snails.