To a stationary observer, a bus moves south with a speed of 12 m/s. A man inside walks toward the back of the bus with a speed of 0.5

To a stationary observer, a bus moves south with a speed of 12 m/s. A man
inside walks toward the back of the bus with a speed of 0.5 m/s relative to
the bus. What is the velocity of the man according to a stationary observer?
A. 11 m/s south
B. 12.5 m/s south
C. 11.5 m/s south
D. 0.5 m/s south