Test and analysis: the red light looks deeper because the refractive index of water to red light is smaller than that to green light. According to the relationship between apparent depth and real depth, the smaller the refractive index, the deeper it looks. From the meaning of the question, it can be seen that the light on the edge of the water surface irradiated by the point light source is totally reflected. From the geometric knowledge, the smaller the refractive index, the larger the radius.
The water area irradiated by point light source is 0, so the water area irradiated by red light is larger.
So choose d
Comments: The key to the problem is to know that the light at the edge of the water surface is only total reflection, which can be easily solved by combining the law of refraction and geometric knowledge.