Answer:

Longest

Explanation:

The visible light spectrum goes from red color to blue color:

• The red wavelength of light has the lowest energy in that spectrum, and as such, it is the longest wavelength.

• Conversely, the blue wavelength of light has the highest energy in that spectrum, and as such, it is the shortest wavelength.

As it has the longest wavelength, it can travel further than other wavelengths, which is why the moon appears red during a lunar eclipse.