Final answer:
The statement that is FALSE about the watermelon's motion is that its speed remains constant. As the watermelon falls, it gains speed due to the acceleration due to gravity. In reality, the watermelon's speed increases as it falls.
Step-by-step explanation:
The statement that is FALSE about the watermelon's motion is d) Its speed remains constant.
As the watermelon falls, it gains speed due to the acceleration due to gravity, so its speed is not constant. This means that option d) is incorrect. In reality, the watermelon's speed increases as it falls, reaching its maximum speed just before hitting the ground.
In contrast, options a) and b) are true statements. The watermelon experiences a constant acceleration due to gravity and gains kinetic energy as it falls. Additionally, c) is also a true statement, as the potential energy of the watermelon decreases as it falls.