(5) Suppose that a client performs an intermixed sequence of (queue) enqueue and dequeue operations. The enqueue operations put the integers 0 through 9 in order onto the queue; the dequeue operations print out the return value. Which of the following sequence(s) could not occur?

a. 0 1 2 3 4 5 6 7 8 9 b. 4 6 8 7 5 3 2 9 0 1 c. 2 5 6 7 4 8 9 3 1 0 d. 4 3 2 1 0 5 6 7 8 9