A review of the cladogram shows a common ancestor for these four types of vertebrates. Which statement BEST explains the genetics represented by the cladogram?

The correct answer for your question is lizards and snakes are more genetically similar than lizards and birds.

Explanation:As already known that the Order of Squamata is the largest order of reptiles but lizards and snakes alone make the largest part of the Squamata. Lizards and snakes are similar in many aspects like cold blood, senses, tongue and reproductive organs.  

bacterium is not correct