Explanation
Correct answer: D.
Choice D is the best answer. The sentence emphasizes a difference between surface-dwelling and cave-dwelling tetras, noting that while surface-dwelling tetras can see, cave-dwelling tetras can’t.
Why the other choices are wrong
Choice A
Choice A is incorrect. While the sentence notes that surface-dwelling and cave-dwelling tetras are different, it doesn’t emphasize any difference between the two populations of tetras.
Choice B
Choice B is incorrect because the sentence explains that cave-dwelling tetras use sensory receptors on their skulls to navigate; it doesn’t emphasize a difference between surface-dwelling and cave-dwelling tetras.
Choice C
Choice C is incorrect. While the sentence notes that there are two different populations of Mexican tetras, it doesn’t emphasize any difference between the two populations.