Explanation

22) Choice D is correct. Because the Komodo dragon, a species of Varanus, is restricted to “four small islands in the archipelago” but “most existing species” of the genus Varanus as a whole live in Australia, the geographical distribution of the genus includes species in both places. The distribution of the Komodo dragon is restricted to only one of these places and is thus more restricted than the genus as a whole, not less restricted. Thus, Choice C is incorrect. Choices A and B are incorrect because the passage does not describe the specific change in the geographic distribution of the Komodo dragon, but rather just describes its present distribution. Choice E is incorrect because the passage does not present its discussion of the Komodo dragon as evidence for either hypothesis of the origin of Varanus but rather as a “related puzzle.”

23) Choice A is correct. The passage provides support for Mertens’ argument by providing later chromosomal evidence as well as geologic evidence but it does not provide nor describe the evidence with which Mertens originally argued. Choices B and E are incorrect because the passage states that early researchers argued for a specific origin for Varanus “because most existing species live in Australia,” which indicates the present-day distribution of species. Choices C and D are incorrect because the passage provides geologic evidence to suggest a possible explanation for how Varanus may have spread to either Australia or the archipelago regardless of its origin.

24) Choice B is correct. The passage presents the “geologic evidence” so as to provide a possible explanation for the prevalence of the various species of Varanus in Australia if indeed Mertens’ theory is correct. But the evidence itself does not rule out the possibility that the earlier theory is correct and that Mertens is not, so the “geologic evidence” cannot rule out either theory. Choice A is incorrect because there is no specific indication that Mertens first provided this evidence, and the chronology of the presentation suggests that he did not. Choice C is incorrect as there is no mention in the passage of a specifically renewed interest in the debate. Choice D is incorrect since the “geologic evidence” does not rule out nor confirm either Mertens’ conclusions or those of earlier researchers.