Analysis of test questions: rapid and direct revelation is called epiphany; Progressive enlightenment is called gradual enlightenment. Epiphany is a kind of inspiration, which makes you suddenly enlightened. For a thing or a truth, you suddenly realize it because of a certain factor or reason. Epiphany requires specific environment and factors, while gradual enlightenment is different, such as meditation, and understanding after long thinking in an ethereal state of mind. B meets the meaning of the question and should be selected; A, c and d are inconsistent with the meaning of the question, so choose B.