Consider a disk that is scheduled as follows: the disk head moves from the first cylinder to the last cylinder repeatedly, processing the I/O requests in various cylinders along the way. That is, after it reaches the last cylinder, it first moves back to the first cylinder, without processing any requests and then resumes processing of requests as it scans from the first cylinder. At time t, let the disk have the following requests in its queue: Request Cylinder
R1 25
R2 12
R3 47
R4 32
R5 74
R6 63
R7 17
R8 91

Let the most recent I/O request processed by the disk be in cylinder 40 (i. e., the disk is scanning from cylinder 40 towards the higher-numbered cylinders at time t). Also, assume that no other requests arrive in the disk queue until all of the above requests are processed. Determine the schedule of processing for the above set of requests.

Based on the schedule, identify the TRUE statement among the following, with respect to the relative order of processing the various requests.

a. R2 is processed immediately after R8.
b. R1 is processed immediately after R4.
c. R4 is the first request processed.
d. R4 is processed immediately after R8