27. Which of the capital letters of the alphabet, when drawn in the most symmetrical way, have the following symmetries? For example, assume that the upper and lower loops of B are the same size.
27.
(a) B, C, D, E, H, I, K, O, X
(b) A, H, I, M, O, T, U, V, W, X, Y
(c) H, I, N, O, S, X, Z