Which of the following choice all contains GCC states? ( ).

参考解析：

根据第二段Oil is central to the six Gulf Co-operation Council (GCC) states, which have used the windfall of the past few years to spend lavishly. Unlike many oil exporters, such as Nigeria and Venezuela, they have可知，Nigeria and Venezuela都不属于GCC成员国。故排除A和B。且可知，GCC是由6个国家构成。根据第三段Moody’s, a ratings agency, this month downgraded Bahrain and Oman and put on watch the other four GCC states: Saudi Arabia, Kuwait, the United Arab Emirates (UAE) and Qatar.可知，GCC是由Bahrain and Oman, Saudi Arabia, Kuwait, the United Arab Emirates (UAE) and Qatar这6个国家构成。故本题正确答案选C。