Final answer:
The package's acceleration just before hitting the ground is -9.8 m/s², as it is in free fall and influenced only by gravity, not the initial upward motion of the helicopter.
Step-by-step explanation:
The package's acceleration just before it hits the ground would be due to gravity, which is 9.8 m/s² downward, regardless of the helicopter moving upward initially. Since the question asks for the acceleration just before impact, the helicopter's initial velocity does not affect the acceleration due to gravity. Therefore, the correct answer is c) -9.8 m/s², assuming the convention that upwards is positive and downwards is negative. The package, once released, is in free fall, and its acceleration is constant and equal to the acceleration due to gravity.