已知ψϴ(Cu+/Cu)=.V；ψϴ(I/I)=.V；ψϴ(Fe+/Fe+)=.V；ψϴ(Sn+/Sn+)=.V，判断下列还原剂的还原性由强到弱的是ACuIFe+Sn+BIFe+Sn+CuCSn+CuIFe+DFe+Sn+ICu