Question

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some rainforests have toucans. toucans are birds. toco toucans are the largest ones. they live only in south america. toco toucans have pretty bills. they are orange with black tips. the bills are big, too. they can be eight inches (20 centimeters) long. scientists wanted to know why their bills are so big. they found that toucans do not sweat. extra heat leaves their bodies through their bills.
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a toucan’s bill keeps it ______.
a cool
b flying
c clean
d fed

Explanation:

The text says toucans don't sweat and extra heat leaves their bodies through their bills. So the bill's function related to heat is to keep the toucan cool. Option A (cool) matches this context. Options B (flying), C (clean), D (fed) don't relate to the heat - regulation function described.

Answer:

A. cool