下列配合物的稳定性，从大到小的顺序，正确的是（）A[HgI]＞[HgCl]＞[Hg(CN)]B[Ni(en)]+＞[Ni(NH)]+＞[Ni(HO)]+C[Co(NH)]+＞[Co(SCN)]＞[Co(CN)]D[Fe(SCN)]＞[Fe(CN)]＞[Fe(CN)]