A ball A is released from rest from the top of a tower. After 2.0 s, another ball B is projected downward from the same point with a speed of 40 m s⁻¹. Take g = 9.8 m s⁻². After how much time, measured from the instant B is projected, will B overtake A?
a) 0.5 s
b) 1.5 s
c) 1.0 s
d) 0.65 s