Systems will limit the time that the program remains in the running state to a fixed length of time corresponding to one or more quanta.

Preemptive systems will limit the time that the program remains in the running state to a fixed length of time corresponding to one or more quanta.
The preemptive systems are also referred to as cooperative multitasking systems. The term preempting describes the act of taking control of the operating system from one task and giving it to another task . These systems have computer operating systems that use some criteria to decide how long to allocate to any one task before giving another task a turn to use the operating system. 

Answerall but the first dimension;