CPUs and operating systems can work in two main types of multitasking modes. What controls access and the use of system resources in preemptive multitasking mode?

A.
The user and application

B.
The program that is loaded into memory

C.
The operating system

D.
The CPU and user

Explanation:
C: Operating systems started out as cooperative and then evolved into preemptive multitasking. With preemptive multitasking, used in Windows 9x, NT, 2000, and
XP, as well as in Unix systems, the operating system controls how long a process can use a resource. The system can suspend a process that is using the CPU (or
other system resources) and allow another process access to it through the use of time sharing. Thus, operating systems that use preemptive multitasking run the show, and one application does not negatively affect another application if it behaves badly. In operating systems that used cooperative multitasking, the processes had too much control over resource release, and when an application hung, it usually affected all the other applications and sometimes the operating system itself. Operating
systems that use preemptive multitasking run the show, and one application does not negatively affect another application as easily.
A is incorrect because the user and application do not control access and the use of system resources in preemptive multitasking mode. The application, however,
has more control over the use of system resources in cooperative multitasking mode. The operating system itself either works in preemptive or cooperative multitasking
modes, not the applications or users.
B is incorrect because as described in answer A, an program does not run in a specific multitasking modethe operating system does. Cooperative multitasking,
used in Windows 3.1 and early Macintosh systems, required the processes to voluntarily release resources that they were using. This was not necessarily a stable
environment because if a programmer did not write his code properly to release a resource when his application was done using it, the resource would be committed
indefinitely to his application and thus unavailable to other processes.
D is incorrect because the user and CPU do not control access and the use of system resources. Instead, the operating system controls the processor time slices that
different processes can be allocated. Multitasking is the way that the operating system uses access to the CPU, which can be either cooperative or preemptive.