GWD 12 _Q28:

Some scientists contend that many species of dinosaur had a metabolism more like a warm-blooded mammal’s than a cold-blooded reptile’s.

that many species of dinosaur had a metabolism more like

that the metabolism of many dinosaur species were more like

that the metabolisms of many species of dinosaurs were more like those of

there were many species of dinosaurs that had metabolisms more like those of

there were many dinosaur species that had a metabolism more like that of

I am not sure whether the answer is A or B Could anyone here help me tackle this problem?

Key: A.

Choice B: matabolism ... were ... you see the problem here?