(1 point) 4 -letter words" are formed using the letters A, B, C, D, E, F, G. How many such words are possible for each of the following conditions? (a) No condition is imposed. Your answer is: (b) No letter can be repeated in a word. Your answer is: (c) Each word must begin with the letter A. Your answer is: (d) The letter C must be at the end. Your answer is: (e) The second letter must be a vowel. Your answer is :