Explanation
Correct answer: D.
Choice D is the best answer. “Based on these models” logically signals that the research finding described in this sentence—that the largest T. rex could have been 70% heavier than the current largest-known specimens—is derived from the computer models described in the previous sentence.
Why the other choices are wrong
Choice A
Choice A is incorrect because “in addition to these factors” illogically signals that the research finding about T. rex size presented in this sentence introduces factors beyond those noted in the previous sentence (growth rate, lifespan, and the size of available fossils). Instead, the finding is derived from the researchers’ models, which incorporated those factors.
Choice B
Choice B is incorrect because “despite these estimates” illogically signals that the research finding about T. rex size presented in this sentence is true despite the previous information about the researchers’ model-generated size estimates. Instead, the finding is derived from the researchers’ models.
Choice C
Choice C is incorrect because “further complicating these issues” illogically signals that the previous information about the researchers’ computer models presents difficulties and that the research finding about T. rex size presented in this sentence adds to those difficulties. Instead, the finding is simply derived from the researchers’ use of the models.