The simulation that would not work for the situation described is:
C) To simulate randomly selecting a letter of the alphabet, assign a one-digit number from 0 to 9 to each letter. Use a random digit table to generate one-digit numbers, ignoring any over 9.
The reason this simulation would not work is that there are 26 letters in the English alphabet (A to Z), and assigning a one-digit number (0 to 9) would not uniquely represent all the letters. Since 10 digits (0-9) cannot map to 26 letters, this simulation is incomplete and cannot accurately represent all the letters of the alphabet.