Exams, grades and marks should be abolished because children’s progress should only be estimated by ______?

参考解析：

推理判断题。根据第三段第五至七句“Let’s end this nonsense of grades, exams, marks. Let us throw them all out, and let children learn what all educated person must some day learn, how to measure their own understanding, how to know that they know or do not know. Let him get on with this job in the way that seems sensible to them”可知，让我们结束这些关于成绩、考试、分数的无稽之谈吧。让我们把它们都扔掉，让孩子们学习所有受过教育的人有朝一日必须学习的东西，如何衡量他们自己的理解力，如何知道他们知道还是不知道。让他以他们认为明智的方式来做这项工作。由此可知，考试、成绩和分数应该取消，因为孩子的进步只能由孩子自己来估计。而不是受过教育的人、他们的父母和老师，因此排除A、C、D选项。故选B。