GRE Text Completion: ETS Fundamental-GRE填空ETS基础 - C621Z50Z5B4O67G0X

The chances that a species will (i)____________ are reduced if any vital function is restricted to a single kind of organ; (ii)____________ by itself possesses an enormous survival advantage. A. persist B. size C. expire D. redundancy E. degenerate F. symmetry