Explanation
Correct answer: C.
Choice C is the best answer. “Granted” logically signals that the following information—that iconicity is not as highly correlated with acquisition as sign frequency—is true in spite of the information about the correlation between iconicity and acquisition in the previous sentence.
Why the other choices are wrong
Choice A
Choice A is incorrect because “in fact” illogically signals that the sentence that follows either emphasizes or refutes the information in the previous sentence regarding the correlation between iconicity and acquisition. Instead, the sentence that follows provides additional information that is true in spite of the preceding information; it neither emphasizes nor refutes that information.
Choice B
Choice B is incorrect because “in other words” illogically signals that the sentence that follows is a restatement of the information in the previous sentence; instead, the sentence that follows provides additional information that is true in spite of the preceding information.
Choice D
Choice D is incorrect because “as a result” illogically signals that the sentence that follows is a result of the information in the previous sentence regarding the correlation between iconicity and acquisition; instead, the sentence that follows is true in spite of the preceding information.