单选题：Which of the following statements is incorrect?
Which of the following statements is incorrect? @[B](1)
A. The long-term scheduler always appears on batch systems, not present on time-sharing OSs like UNIX
B. The medium-term scheduler controls the degree of multiprogramming
C. The long-term scheduler is invoked infrequently than the short-term scheduler.
D. The short-term scheduler selects which process should be executed next and allocates CPU.
A.The long-term scheduler always appears on batch systems, not present on time-sharing OSs like UNIX
B.The medium-term scheduler controls the degree of multiprogramming
C.The long-term scheduler is invoked infrequently than the short-term scheduler.
D.The short-term scheduler selects which process should be executed next and allocates CPU.
答案：B
A. The long-term scheduler always appears on batch systems, not present on time-sharing OSs like UNIX
B. The medium-term scheduler controls the degree of multiprogramming
C. The long-term scheduler is invoked infrequently than the short-term scheduler.
D. The short-term scheduler selects which process should be executed next and allocates CPU.
A.The long-term scheduler always appears on batch systems, not present on time-sharing OSs like UNIX
B.The medium-term scheduler controls the degree of multiprogramming
C.The long-term scheduler is invoked infrequently than the short-term scheduler.
D.The short-term scheduler selects which process should be executed next and allocates CPU.
答案：B