Test analysis: This question mainly examines students' ability to accurately interpret material information. According to the text of the material, "in order to prevent the empire from splitting again because of the rise of local warlords, ... at the expense of military strength, this puts them at a disadvantage in dealing with aggressive barbaric neighbors." It means that in order to prevent the local separatist forces from weakening the local military strength too much, the rulers are unable to resist the military attacks of ethnic minorities, which is consistent with the military characteristics of the Song Dynasty, so the answers of C and A B D are inconsistent with the above characteristics.