题目

If you still know little about the “IMF”, it’s time you started to read about it, for it has been a hot issue of the whole world． The International Monetary Fund （IMF） is one of the international financial（金融的） institutions, which works for global growth and economic stability．It provides policy advice and financing to members in economic difficulties and also works with developing nations to help them achieve economic stability and reduce poverty．The“ IMF” currently has a near-global membership of 185 countries． To become a member, a country must apply for it a集合{1，2，3}的真子集的个数为（ ）A．5B．6C．7D．8