For an object released from rest and allowed to fall freely near Earth’s surface, which of the following best represents the shape of its distance–time (s–t) graph?
(a) Straight line passing through the origin
(b) Exponential curve rising slowly at first and then steeply
(c) Parabola opening upward with vertex at the origin
(d) Curve that rises quickly at first and then flattens out like s∝t