30. What does the article mention about the process of metamorphosis?
(A) It always takes place on land.
(B) It only happens to amphibians.
(C) It is longest for frogs.
(D) It differs for each amphibian species.
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統計: A(0), B(20), C(5), D(100), E(0) #2342157
統計: A(0), B(20), C(5), D(100), E(0) #2342157