阅读材料: “西气东输”一线工程管道西起新疆塔里木盆地的轮南油田,向东到达上海,全长4000km,于2004年10月1日全线贯通并投产。由一条干线和八条支干线组成的“西二线”,西起新疆霍尔果斯,东达上海,南抵广州、香港,横贯中国东西两端,横跨15个省区市及特别行政区,年输气能力达300亿立方米,可稳定供气30年以上。
阅读下列材料,从A、B、C、D四个选项中选出最佳答案,并把答题卡上对应题目的答案标号涂黑。
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若地磁场在某区域的磁场强弱和方向处处相同,小明在该区域某处竖直拿着闭合的矩形导电线圈面向南方,如图,则能使线圈中产生感应电流的操作是( )
①人民群众是物质财富的创造者
②人民群众在经济社会发展中起主体作用
③人民群众是创造社会历史的源泉
④人民群众是社会存在和发展的基础