A body of mass 10 kg is moving with a constant velocity of 10 m/s. When a constant force acts for 4 seconds on it, it moves with a velocity 2 m/sec in the opposite direction. The acceleration produced in it is. A. 3m/s^2. B. -3m/s^2. C.0.3m/s^2. D. -0.3m/s^2