[单项选择]Do you know why different animals or pests have their special colors Colors in them seem to be used mainly to protect themselves.
Some birds like eating locusts(蝗虫), but birds cannot easily catch them. Why It is because locusts change their colors together with the change of the colors of crops. When crops are green, locusts look green. But as the harvest time comes, locusts change to the same brown color as crops have. Some other pests with different colors from plants are easily found and eaten by others. So they have to hide themselves for lives and appear only at night.
If you study the animal life, you’ll find the main use of coloring is to protect themselves. Bears, lions and other animals move quietly through forests. They cannot be easily seen by hunters. This is because they have the colors much like the trees.
Have you ever found an even more strange act A kind of fish in the sea can send out a kind of very black liquid(液体)when it faces danger. While the liq
A. they have the colors much like the trees
B. they move quietly
C. they like brown and grey colors
D. they live in forests

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