[单选题]Choose the closest paraphrased version after the following sentence or the italicized part.One of the most important things I've learned is how much there is to learn, and how much I don't yet know.（ ） A ...that in the vast sea of knowledge I'm just a little drop. B ...that I know very little and there's much for me to learn. C ...that I am ignorant, so I must learn what I do not know. D ...that compared with what I don't know, my knowledge is limited.