TOEFL Reading: ETS-TOEFL阅读机经 - 6_M806SA3M7Z15MNL$

Why does the author ask the question "What sorts of ecological advantages could outweigh these complications?" A. To suggest that there is no single advantage but many advantages B. To challenge the idea that metamorphic transformations are always beneficial C. To prepare readers for a discussion that may explain why metamorphosis occurs D. To identify a particular aspect of metamorphosis that is poorly understood