Which of the following commands enables the setuid (suid) permission on the executable called /bin/foo?

Which of the following commands enables the setuid (suid) permission on the executable called /bin/foo?

A.
chmod 1755 /bin/foo

B.
chmod 4755 /bin/foo

C.
chown u-s /bin/foo

D.
chmod 755+s /bin/foo