求助大全12

12.         A little under a million years ago, the briny waters of the Baltic Sea began flooding into the cold North Atlantic: geologists are still debating whether the flood was gradual or created a cataclysm. C D

(A) whether the flood was gradual or created a cataclysm

(B) if the flood was gradual or created a cataclysm

(C) about whether the flood was gradual or cataclysmic

(D) whether the flood was gradual or cataclysmic（D）

(E) whether the flood was gradual or it created a cataclysm

当时选c的时候感觉debate over/about 词组要完整。有没有大牛解释一下？