Explanation
Correct answer: B.
Choice B is the best answer because it most logically completes the text’s discussion of the utility of the Oase 1 fossil to paleoanthropologists. As used in this context, "discern" means to detect or recognize something, especially something hidden or obscure. The text indicates that the Oase 1 fossil can help paleoanthropologists recognize patterns in the evolutionary process and shed light on ("illuminate") the period in which Oase 1 lived. Thus, the fossil will enable researchers to gain insights into, or discern, facts that are still not well understood.
Why the other choices are wrong
Choice A
Choice A is incorrect because in this context, "exploit" would suggest that the paleoanthropologists are using "steps in the evolution of hominids," which does not make logical sense. Rather, the text is about how the Oase 1 fossil could help paleoanthropologists learn about hominid evolution and the Pleistocene epoch more generally.
Choice C
Choice C is incorrect because in this context, "prioritize" would suggest that either the paleoanthropologists are placing more importance on "steps in the evolution of hominids" than they are on something else not identified in the text or that they are placing these steps in some sort of order. Rather, the text is about how the Oase 1 fossil could help paleoanthropologists learn about hominid evolution and the Pleistocene epoch more generally.
Choice D
Choice D is incorrect because to say that paleoanthropologists could "yield" or generate "steps in the evolution of hominids" doesn’t make sense. The researchers may develop new insights into those evolutionary steps, but they do not create those steps themselves. Rather, the context makes it clear that they are detecting or discovering patterns based on their study of the Oase 1 fossil.