Question

How is color related to wavelength?

Answer 1

Answer to d.
Color travels in waves which are loosely divided into into short medium and long in length. because color travel at different wavelengths some are easier to see than others but the amount of light is also a factor. in general however green is the most visible color from a distance.
answer to c.
No it depends on the time of day whether it is light or dark because clors stand out in different wavelenghts
answer to b.
yes that's absolutely true.
answer to a.
No purple is the shortest wavelength and the highest frequency