A parachutist is falling at terminal velocity, without her parachute open.
She now opens her parachute.
What is the direction of her motion, and what is the direction of her acceleration, immediately after she opens her parachute?
When the parachutist is falling at terminal velocity, the upwards air resistance is equal to the weight of the parachutist. The resultant force is zero and the velocity is downwards.
When the parachute opens, the air resistance increases and is now greater than the weight.
The resultant force is now upwards and the acceleration is upwards. The velocity is still downwards.
Answer is B.