A cryptographer intercepted an enemy message that is in code. He knows that the code is a simple substitution of numbers for letters. Which of the following will be least helpful in breaking the code? a. b. c. d. Knowing the frequency with which the vowels of the language used. Knowing the frequency with which two vowels appear together in the language. Knowing the frequency with which odd numbers appear relative to even numbers in the message. Knowing every word in the language that begins with the letter "r