More than five thousand years ago, Chinese scholars accurately described the flow of blood as a continuous circle controlled by the heart, but it went unnoticed in the West.
(A) but it went
(B) but it was
(C) although it was
(D) but the discovery went（D）
(E) although the discovery was
go unnoticed与is unnoticed有无区别，although 是否只能放在句首？
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