Correct option (B) 480 N
Explanation:
Initial momentum of the ball = (150/1000) x 12 = 1.8 kg m/sec
Final momentum of the ball = –(150/1000) x 20 = – 3.0 kg m/sec
Change in momentum = 4.8 kg m/sec.
Average force exerted = impulse/time = (4.8 kg m/sec) / 0.01 s