Final answer:
A fast-moving ball is more visible when it is yellow-green because that color is where our eyes are most sensitive, due to peak cone cell sensitivity and the resulting efficient light signal conversion.
Step-by-step explanation:
The question pertains to the visibility of moving objects based on their color, which is a topic that involves the physics of light and human vision. The most visible color for a fast-moving ball is one that the human eye is the most sensitive to. Research suggests that the human eye is most sensitive to colors around the yellow-green range of the spectrum. This is because light in this part of the spectrum has a wavelength that is well within the range of peak sensitivity for the human eye's cone cells, which are responsible for color vision. The yellow-green color corresponds to a wavelength of approximately 555 nanometers, which is where our eyes' photoreceptors are most efficient at converting light into signals for our brains to process.
Additionally, colors like yellow-green stand out well against a variety of backgrounds, which is another reason why such a ball would be easier to see while in motion when compared to colors with longer or shorter wavelengths that are not as easily detected by the human eye. Therefore, option C. yellow-green is the best answer.