问题如下图：
选项：
A. 
B. 
C. 
解释：
好像app里面的中文解释错了
NO.PZ2016010802000188 问题如下 If Brazil anSouth Afrihave free tra with eaother, a common tra poliagainst all other countries, but no free movement of factors of proction between them, then Brazil anSouth Afriare part of A.customs union. B.common market. C.free tra area (FTA). is correct.A customs union exten a free tra area (FTnot only allowing free movement of goo anservices among members, but also creating common tra poliagainst non-members. Unlike a more integratecommon market, a customs union es not allow free movement of factors of proction among members.考点free tra area自由贸易只要求商品的自由流动，C不入选。common market仅仅还要求贸易国间的生产要素能够自由流动，所以B不入选。customs union 要求所有成员国对非成员国实施同一的贸易限制措施，所以A入选。 。
NO.PZ2016010802000188 题目中提到，no free movement of factors of proction between them，而customs union allow free movement of goo anservices among members。
我问过英语母语的美国朋友，这里的against 的表达，她理解为只有这两个国家相互协议，不应用于其他国家的。烦请确认一下这个题目吧？应该正确答案为C吧？谢谢！
为什么C不对？为什么C不对？
