最有影响的商品卡特尔是由13个成员国组成的石油输出国组织。

最有影响的商品卡特尔是由13个成员国组成的石油输出国组织。
【正确答案】：The most influential commodity cartel is the Organization of Petroleum Exporting Countries (OPEC) composed of thirteen members established in 1960 with headquarters at Vienna.
【题目解析】：参见教材P40。