 
 <translate> Another way: Any letter (x, y, z, w, p, q) can be included or not. So, we have 2^6 combinations - 1 empty combination = 63 combinations The final answer: (D). <ibo> Ụzọ ọzọ: A pụrụ ịgụnye mkpụrụ akwụkwọ ọ bụla (x, y, z, w, p, q) ma ọ bụ ghara ịgụnye ya. Ya mere, anyị nwere 2 n'ike nke 6 jikọtara - 1 oghere jikọtara = 63 jikọtara Azịza ikpeazụ: (D). 