单选题：What is the purpose of system calls?
What is the purpose of system calls?@[B](1)
A. System calls allow user-level processes to gain resources from the operating system.
B. System calls are the standard interface between a user process and a kernel process.
C. System calls allow user-level processes to request services of the operating system.
D. There is no real purpose to system calls.
A.System calls allow user-level processes to gain resources from the operating system.
B.System calls are the standard interface between a user process and a kernel process.
C.System calls allow user-level processes to request services of the operating system.
D.There is no real purpose to system calls.
答案：B
A. System calls allow user-level processes to gain resources from the operating system.
B. System calls are the standard interface between a user process and a kernel process.
C. System calls allow user-level processes to request services of the operating system.
D. There is no real purpose to system calls.
A.System calls allow user-level processes to gain resources from the operating system.
B.System calls are the standard interface between a user process and a kernel process.
C.System calls allow user-level processes to request services of the operating system.
D.There is no real purpose to system calls.
答案：B