Final answer:
An afterimage is a visual sensation that continues after the stimulus is removed, often demonstrating the opponent-process theory of color vision as retinal ganglion cells adjust their firing rate. The correct option is A.
Step-by-step explanation:
An afterimage can best be defined as a sense experience that occurs after a visual stimulus has been removed.
This phenomenon is often observed in a scenario where you might stare at a colored image for a period of time and then look away to a blank surface, only to still see the image.
For example, if you were to stare at a green dot for an extended period and then look at a blank white screen, you would perceive a negative afterimage.
This is because of the opponent-process theory which suggests that staring at one color fatigues the cells responding to that color and when you look away, you see its opposite color.
Another example involves looking at a flag with certain colors and then looking at a white surface, where you would then see the flag in different colors.
This occurs because your retinal ganglion cells adjust their firing rate when the stimulus is removed, creating the perception of the opposite colors in your visual field. The correct option is A.