单选题：Which of the following is a probable invocation flow?

Which of the following is a probable invocation flow?@[A](1)
A. fork -> sys_fork -> do_fork
B. do_fork -> fork -> sys_fork
C. vfork -> do_fork -> sys_vfork
D. fork -> do_fork -> sys_fork




A.fork -> sys_fork -> do_fork
B.do_fork -> fork -> sys_fork
C.vfork -> do_fork -> sys_vfork
D.fork -> do_fork -> sys_fork


答案：A