Step 1: In a mirror the order of the letters is reversed and each letter is flipped left–right. Step 2: For a word to look the same, the word must read the same backwards and every letter must be symmetrical about a vertical line. Step 3: Letters symmetrical about the vertical line include A, H, I, M, O, T, U, V, W, X, Y. Step 4: MOM: reversed it is still MOM, and M and O are both symmetrical. So it looks the same. Step 5: DAD, RAT and BED contain D, R, B or E, which look different when flipped. Answer: MOM.