I think the puck pushes the stick backwards
Answer:
Acceleration of the car will be 
Explanation:
We have given mass of the ball m = 1600 kg
Force in north direction F= 7560 N
Resistance force which opposes the movement of car 
So net force on the car 
According to second law of motion we know that F=ma
So 

It will sink because mass does not affect the physical properties of the object.
the answer is d they are essential to all ecosystems