2.The price ---- ,but I doubt whether it will remain so.

2.The price ____ ,but I doubt whether it will remain so.
A.went down B.will go down
C.has gone down D.was going down
选择B对吗?
这是虚拟语气的句子还是whether引导的名词从句.还有在这个句子中时态怎样用啊?请高人帮我讲讲.