Final answer:
A free-body diagram at the top of a loop would depict an object as continuing to move and not at rest. This is necessary for the object to maintain its trajectory around the loop due to the forces, such as gravity and centripetal force, acting on it.
Step-by-step explanation:
The student's question refers to the situation of an object at the top of a loop, specifically a free-body diagram depicting this scenario.
In the context of physics, a free-body diagram is a representation showing all the forces acting upon an object. When considering an object at the top of a loop, such as a roller coaster loop or a block sliding around a loop-the-loop apparatus, it would have to keep moving to maintain its trajectory around the loop.
If it were to be at rest at the top of the loop, it would fall straight down due to gravity, which contradicts the notion of a loop-the-loop where the object is expected to travel around the loop.
Therefore, the correct answer to whether a free body diagram at the top of the loop should show the object as continuing to move or being at rest is A) Keep moving.
This is a concept from kinetics and dynamics, related to circular motion and the forces involved in such motion like the centripetal force that must be in action to keep the object moving in a circular path.