19- If we perform the following sequence: enqueue(10), enqueue( 5), dequeue(), enqueue(13), enqueue(6). enqueue, dequeue(), dequeuel), enqueue(2), enqueue(8), dequeue().enqueue(20). What is the front and rear index positions and what is the number of elements in the simple queue? a) front: 4, rear: 7. and number of elements: 8 b) front: 7. rear: 4, and number of elements: 4 c) front: 4. rear: 7. and number of elements: 4 d) front: 1.rear: 20, and number of elements: 2