When the paratrooper is dropped from the aeroplane, the parachute does not open for a white. During this time interval, its speed increases linearly with time. Using the first equation of motion: v = u + at Initial velocity, u = 0 [As paratrooper is dropped] Acceleration, a = g (acceleration due to gravity) ⇒ v = 0 + gt = gt ⇒ v α t [as g = 9.8 m∕s2 : constant] When the parachute opens, speed of the paratrooper decreases exponentially. This is best illustrated by the graph in option 'D'. Hence, option ’D' is correct