Which of the following option correctly describes the variation of the speed and acceleration of a point mass falling vertically in a viscous medium that applies a force F = -kv, where k is a constant, on the body?

When the point mass will start falling its initial velocity will be zero and it will have maximum acceleration. After the mass will attain a steady state velocity, its acceleration will become zero due to the influence of viscous force acting on it. This scenario is clearly depicted in the graph of option D.