Imagine an old single-programming system equipped with a CPU, a disk, a printer, and a reader. At the end of a program execution, the system reports the accumulated percentage usage of the four components. The exact pattern of the program's activities is not known: the report includes one number per device. According to the report, a certain program spends 70% of its time using the CPU, with the remaining 30% equally partitioned among the remaining three hardware components. This is all we know about the program. By how much will the execution time of the program decrease when the disk is replaced with a new version being twice as fast as the previous one? a. by 1% b. by 5% c. by 10% d. by 20% e. by 40% f. by 50% g. it can be any number between 0% and 30%