Starting with a, if the first half of the sentence is correct, that is, D is second,

Then if B knows that E is the fourth (C is definitely wrong in the second place), D knows that C is the third and E knows D is the fifth, then it is found that both sentences of C are completely wrong and fail.

Therefore, if the second half of the sentence A is right, that is, B is the third, then D will know that A is the fourth, B will know that C is the second, E will know that D is the fifth, and C will know that E is the first, and it will be successful.

Then the rankings of ABCDE are: 4325 1.