Explanation
Correct answer: B.
Choice B is the best answer. “Instead” logically signals that the information about the researchers’ discovery in this sentence—that jorō spiders are gentle giants who “freeze” in place when disturbed—contradicts their initial hypothesis about the spiders’ aggressiveness described in the previous sentence.
Why the other choices are wrong
Choice A
Choice A is incorrect because “therefore” illogically signals that the discovery about jorō spiders’ gentleness is a result of the initial hypothesis about their aggressive behavior. Instead, the sentence presents information that contradicts the initial hypothesis.
Choice C
Choice C is incorrect because “for example” illogically signals that the discovery about jorō spiders’ gentleness exemplifies the initial hypothesis about their aggressive behavior. Instead, the sentence presents information that contradicts the initial hypothesis.
Choice D
Choice D is incorrect because “in other words” illogically signals that the discovery about jorō spiders’ gentleness is merely restating or rephrasing the initial hypothesis about their aggressive behavior. Instead, the sentence presents information that contradicts the initial hypothesis.