What is the purpose of file extensions? A. They execute the mail merge function, B. They tell the operating system what kind of document you are creating. O C. They run the spelling checker and grammar checker features. D. They set up your files in an organized hierarchy.

3. bob is arguing that if you use output feedback (ofb) mode twice in a row to encrypt a long message, m, using the same key each time, it will be more secure. explain why bob is wrong, no matter what encryption algorithm he is using for block encryption (15 points).

Look at the far left lane in the picture. explain what the red car is doing and what it needs to do to travel safely.

1. ask the user how many questions are in the quiz. 2. ask the user to enter the key (that is, the correct answers). there should be one answer for each question in the quiz, and each answer should be an integer. e.g., 34 7 13 100 81 3 9 10 321 12 might be the key for a 10-question quiz. you will need to store the key in an array. 3. ask the user to enter the answers for the quiz to be graded. there needs to be one answer for each question. note that these answers do not need to be stored; each answer can simply be compared to the key as it is entered. 4. when the user has entered all of the answers to be graded, print the number correct and the percent correct. 5. add a loop so that the user can grade any number of quizzes with a single key. after the results have been printed for each quiz, ask "grade another quiz? (y/n)." note: you only have one array (the key). you are not creating a new key for each set of quiz answers.