题型分类:细节题
题干分析:提问的是具体的某一种方法相关的信息,属于细节题
选项分析:仍然是注意师生互动,通过男生的发言,引出了 stratigraphy 这一方法,教授进行了说明, 用 but 提示了转折,同时 only 提示了仅仅适用什么情况,之后用 a problem with this 提示了这个方法的问题:an object could have been carried around... used for several generations before it was discarded,用 so 提示了总结:might be much older than the layer, or even the site, where it was found,因此选项 B 正确。