单选题 The San Andreas fault is ______.

A、 an active fault system
B、 a place where earthquakes have been predicted accurately
C、 a place where earthquakes have been controlled
D、 the location of the Rocky Mountain

【正确答案】 A

【答案解析】[试题分析] 细节题。
[详细解答] 根据第四段第一句To answer the first question，scientists are looking very closely at the most active fault systems in the country，such as the San Andreas fault in California．的表述，不难判断A为正确答案。