Select the letter that can replace the question mark (?) in the following series.

A, T, E, U, I, V, O, W, ?, X

U

Logic here is :

Every 3rd Alphabet are correlated to each other  in such a way that within correlated alphabets vowels are inserted in series (A , E , I , O ,U )   .

A, T, E, U, I, V, O, W, ?, X

A(vowel) , T , E(vowel) , T + 1 = U , I(vowel) , U + 1 = V , O(vowel) , V + 1 = W , U (vowel) , W + 1 = X

Ans = U