Final answer:
The input force in a lever system is the force applied by the person, while the output force is the force that lifts the load. Answer A is correct for the situation described.
Step-by-step explanation:
In a situation where a person uses a lever to lift a large rock, the input force is the force applied by the person to the lever. The output force is the lifting force that actually raises the rock. Therefore, the correct answer is A) Input Force: Force applied by the person; Output Force: Force required to lift the rock.
Levers are simple machines that make work easier by allowing a smaller input force to lift a heavier load over a shorter distance. The effectiveness of a lever is determined by the positions of the fulcrum, the input force, and the output force, along with the lengths of the arms on either side of the fulcrum.