What letters of the English alphabet have reflectional symmetry about?

(а) a vertical mirror

(b) a horizontal mirror

(c) both horizontal and vertical mirrors

(a) The letters of English alphabet having reflectional symmetry about a vertical mirror are:

A, H, I, M, O, T, U, V, W, X, Y

(b) Letters of the English alphabets having reflectional symmetry about a horizontal mirror are:

B, C, D, E, H, I, O, X

(c) Letters of the English alphabet having reflectional of symmetry about vertical and horizontal mirror are:

O, X, I, H.