The files that a company has for its employees dealing with utilities occupy 100, 120, 60, 90, 110, 45, 30, 70, 60, 50, 40, 25, 65, 25, 55, 35, 45, 60, 75, 30, 120, 100, 60, 90, 85 sectors. If, after operating systems are installed, a disk can store up to 480 sectors, determine the number of disks needed to store the utilities when the specified heuristic is used to pack the disks with files. Give your answers as whole numbers. (a) next fit: (b) next-fit decreasing: (c) first fit: (d) first-fit decreasing: