阅读以下说明，回答问题。
[说明]
Linux系统开机引导时首先启动内核，由内核检查和初始化硬件设备，载入设备的驱动程序模块，安装root文件系统，然后内核将启动一个名为init的进程。在init运行完成并启动其他必要的后续进程后，系统开始运行，引导过程结束。init进程启动时需要读取inittab配置文件，该文件确定init在系统启动和关机时的工作特性。典型的inittab文件内容见以下清单：
#
#inittab This file describes how the INIT pT ocess should set up
#the system In a certain run-level．
#
#Default runleve1.The runlevels used by RHS are：
#0-halt(Do NOT set initdefault to this)
# 1-Single user mode
# 2-Multiuser，without NFS(The same as 3，if you do not have networking)
# 3-Full multiuser mode
# 4-unused
# 5-X11
# 6-reboot(Do NOT set initdefault to this)
#
id:5:initdefault:
#System initialization．
s1::sysinit:/etC/rc.d/rc.sysinit
10:0:wait:/etc/rc.d/rc 0
11:1:wait:/etc/to.d/rc 1
12:2:wait:/etc/rc.d/rc 2
13:3:wait:/etc/rc.d/rc 3
14:4:wait:/etc/rc.d/rc 4
15:5:wait:/etc/rc.d/rc 5
16:6:wait:/etc/rc.d/rc 6
#Trap CTRL-ALT-DELETE
Ca::ctrlaltdel:/sbir/shutdown-t3-r now
#When our UPS tells us power has falled,assume we have a few minutes
#of power left. Schedule a shutdown for 2 minutes from now．
#This does，of course，assunle you have powerd installed and your
#UPS connected and working correctly．
pf::powerfail:/sbin/shutdown-f-h+2 "Power Failure；System Shutting Down"
#if power was restored before the shutdown kicked in，cancel it．
Pr:12345:powerokwait:/sbin/shutdown-c "PowerRestored；Shutdo、vn Cancelled"
#Run gettys in standard runlevels
1:2345:respawn:/sbin/mingetty tty1
2:2345:respawn：/sbin/mingetty tty2
3:2345:respawn：/sbin/mingetly tty3
4:2345:respawn：/sbin/mingetty tty4
5:2345:respawn：/sbin/mingetty try5
6:2345:respawn：/sbin/mingetty tty6
#Run xdm in runlevel 5
x:5:respawn:/etc/X11/prefdm -nodaemon
root用户执行“ps aux | grep init”命令，得到init的PID是______。
A．0
B．1
C．2
D．3
