Final answer:
The 200 kg box being pulled at a constant speed is an example of Newton's first law of motion.
Step-by-step explanation:
The subject of this question is Physics. The question asks which of Newton's laws applies to a 200 kg box being pulled at a constant speed.
The correct answer is Newton's first law, also known as the law of inertia. This law states that an object will continue to be in a state of rest or move at a constant speed in a straight line unless it is compelled to change by an outside force.
In this case, the box is being pulled at a constant speed, which means there is no change in its motion. Therefore, Newton's first law applies.