Please read the conclusion of the sample essay “Why We Need Mistakes,” and answer the following questions. ①Since mistakes will eventually benefit us, we should not be afraid of making mistakes. ②If we treat them properly and intelligently, we will learn from them and make progress. ③John Powell, a well-known British musician, once points out, “The only real mistake is the one from which we learn nothing.” 1. In the concluding paragraph of “Why We Need Mistakes,” which sentences reinforce the thesis and supporting points of the essay?
选项：

A:The first sentence ;
B:The second sentence ;
C:The first and the second sentences;
D:The last sentence