ANS:B - an acceleration

1. Intentional Acceleration: The lift may be designed to accelerate downward to reach a certain speed, for instance, if it's just starting its descent or if it's designed to speed up for efficiency reasons.
2. Gravitational Acceleration: In most cases, when a lift descends, it experiences a gravitational force pulling it downward. If the lift is moving freely (without any external forces acting on it), it will accelerate downwards due to gravity. The acceleration due to gravity near the Earth's surface is approximately 9.81 m/s².
3. Motor Acceleration: In some situations, the lift may be driven by a motor that provides an additional downward force to accelerate the lift downward.