A decision to set up a world org

A decision to set up a world organization，the United Nations，was made at ___________.
A、Yalta Conference
B、Potsdam Conference
C、Teheran Conference
D、Paris Conference
【正确答案】：A
【题目解析】：本题考查雅尔塔会议。根据课本P213可知，雅尔塔会议上作出了建立一个世界组织——联合国的决定。