单选题：Which of the following is most appropriate?

Which of the following is most appropriate?@[D](1)
A. sys_clone is implemented by sys_fork
B. sys_fork is implemented by sys_vfork
C. sys_vfork is implemented by sys_clone
D. sys_fork is implemented by do_fork



A.sys_clone is implemented by sys_fork
B.sys_fork is implemented by sys_vfork
C.sys_vfork is implemented by sys_clone
D.sys_fork is implemented by do_fork


答案：D