The Environmental Protection Agency frequently puts mandatory controls on toxic substances that present as little risk as one in a million chances to cause cancer.
啊!!!GWD17里面的题啊!我是这样理解的,one chance in a million中的in a million(cases)是修饰one chance的,意思是指在million个cases中只有一个case有chance(of causing cancer),而one in a million chances中one应该只能用作代词,结果没有指代对象。。。话说我也错了,跟楼主一样选A了。。。真心是乱理解的,不知道对不对