A stone is dropped from a window of a running train with a velocity of 36 m/s. What is the magnitude and direction of the net force acting on the stone?
a) Magnitude: 9.8 m/s², Direction: Downward
b) Magnitude: 36 m/s, Direction: Forward
c) Magnitude: 0 N, Direction: Stationary
d) Magnitude: 9.8 m/s², Direction: Forward