Marine biologists suspect that the reason we rarely see giant squids is that they inhabit the "midnight zone" of the ocean, a depth where sunlight does not penetrate, rendering the creatures effectively _______ to observers on the surface.
Which choice completes the text with the most logical and precise word or phrase?
intelligible
invisible
obvious
superior
Correct Answer: B
Choice B is the best answer. The text explains that sunlight doesn't reach them. Therefore, they are "invisible" (unable to be seen) to observers who rely on light.
Choice A is incorrect because "intelligible" means understandable. Choice C is incorrect because "obvious" means easily seen. Choice D is incorrect because while they might be superior swimmers, the specific quality preventing detection is that they cannot be seen.