Answer:
The best statement that explains the student's observation is: "The water is not a smooth surface after the rock is dropped in the pond." When the rock is dropped in the pond, it creates ripples and waves that disturb the smooth surface of the water. As a result, the reflection becomes less clear because the disturbed surface scatters the light and creates a distorted image. This is a common phenomenon observed when a disturbance is created on the surface of water, like when you throw a stone or object into it.