Digging in sediments in northern China, evidence has been gathered by scientists suggesting that complex life-forms emerged much earlier than they had previously thought.
(A)evidence has been gathered by scientists suggesting that complex life-forms emerged much earlier than they had
(B)evidence gathered by scientists suggests a much earlier emergence of complex life-forms than had been
(C)scientists have gathered evidence suggesting that complex life-forms emerged much earlier than
(D)scientists have gathered evidence that suggests a much earlier emergence of complex life-forms than that which was
(E)scientists have gathered evidence which suggests a much earlier emergence of complex life-forms than that
题目分析：划线外的digging就提示AB不可以了，做出dig这个动作的应该是个人，D和E的than后面用that which was和that显然没必要，太罗嗦了，意思又没什么变化用这个wordy的表达方式干什么，选C
