Which of the following elements in the debate over the origin of Varanus is NOT provided in the passage? A. The evidence that led Mertens to argue that Varanus originated in the Indo-Australian archipelago. B. The evidence that led early researchers to argue that Varanus originated in Australia. C. A possible explanation of how Varanus might have spread to the Indo-Australian archipelago if it had originated in Australia. D. A possible explanation of how Varanus might have spread to Australia if it had originated in the Indo-Australian archipelago. E. An indication of the general present-day distribution of Varanus species between Australia and the Indo-Australian archipelago.