how can this best be achieved to automatically execute when entering runlevel 3?

You have written a little startup script (/usr/local/bin/startup.sh) that should automatically execute when entering runlevel 3. According to the standards, how can this best be achieved?

A.
chmod 700 /usr/local/bin/startup.sh; cd/etc/init.d/rc3.d/; ln -s /user/local/bin/startup.sh

B.
chmod 700 /usr/local/bin/startup.sh; cd/etc/init.d/rc3.d/; ln -s /user/local/bin/startup.sh S99startup.sh

C.
chmod 700 /usr/local/bin/startup.sh; cd/etc/init.d/rc3.d/; ln /user/local/bin/startup.sh

D.
chmod 700 /usr/local/bin/startup.sh; cd/etc/init.d/rc3.d/; ln -s /user/local/bin/startup.sh /usr/locl/bin/startup.sh

E.
chmod 700 /usr/local/bin/startup.sh; cp /user/local/bin/startup.sh /etc/init.d/rc3.d/S99Startup.sh