"Usefulness is truth" is a famous proposition of pragmatism about truth, which was first put forward by william james, an American philosopher and the real founder of pragmatism. He believes that "it is useful because it is true" or "it is true because it is useful." These two sentences have the same meaning. James believes that an idea is truth as long as it can link old and new experiences and bring concrete benefits and satisfaction to people; Whether an idea is true or not lies not in whether it conforms to objective reality, but in whether it has utility.

The main points of pragmatism summarized by Feng Youlan are the most concise and clear. Feng said in "Preface to Sansongtang": "The characteristic of pragmatism lies in its true theory. His theory of truth is actually an agnosticism. It holds that knowledge comes from experience and what people can know is limited to experience. As for what is behind the experience, it is unknowable. There is no need to ask this question. This question is meaningless. Because in any case, it is impossible for people to go out of the scope of experience and have any understanding. To solve this problem, we have to rely on experience. The so-called truth is nothing more than an explanation of experience, which is meaningful to complex experience. If the explanation makes sense, it is the truth and is useful to us. Usefulness is truth. There is no such thing as objective truth. "

According to Feng Youlan, B should be chosen.