If it is possible to make only one meaningful word with the first, third, fifth, and the ninth letters of the word ‘CURVATURE’, which would…

If it is possible to make only one meaningful word with the first, third, fifth, and the ninth letters of the word ‘CURVATURE’, which would be the second letter of the word? If more than one such word can be formed, give X as the answer. If no such word can be formed, give K as your answer.