Question

Corals are colonial animals that resemble humans in one

respect: they’re great engineers. Corals construct reefs by excreting calcium carbonate. Hundreds of billions of individual corals working at this project, generation after generation, create these enormous structures. And these structures are crucial to marine life. _________. And water that’s low in nutrients should be, and generally is, low in life. But coral reefs are full of life; the density and diversity of life on a healthy reef may be greater even than in a rain forest. In each of the following questions a short passage is given with one of the lines in the passage missing and represented by a blank. Select the best out of the five choices given to make the passage complete and coherent (Coherent means logically complete and sound)

A In the tropics, the oceans tend to be very low in nutrients, because the water doesn’t turn over very much.

B Corals themselves are models of cooperation; they house single-celled plants, tiny algae that use the nutrients the corals excrete.

C And the reason for that, it seems, is that reefs are like bazaars, where all sorts of creatures congregate and swap with each other what they need to survive.

D It contains a lot of nutrients, and corals, as I mentioned, thrive in nutrient-poor waters.

E Even though corals are relatively simple creatures, or perhaps because they are simple creatures, they are very sensitive to changes in their surroundings.

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Corals are colonial animals that resemble humans in one

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