Which visible colors of light has the longest wavelength?

Red has highest wavelength

Explanation:

Electromagnetic radiation is defined as the radiation which is associated with both electrical and magnetic component. These radiations travel in vacuum as well and travel with the speed of light.

The Electromagnetic visible spectrum involves violet, indigo, blue , green, yellow, orange and red which are arranged in order of increasing wavelength and decreasing frequency.  

Thus red has highest wavelength and blue has lowest wavelength.

this allows people to make the best decision or pursue the best option. when alternatives are weighed using their advantages and disadvantages, the option whose disadvantages outweigh the advantages (based on a qualitative or quantitative analysis) are shunned while those whose advantages outweigh their disadvantages are pursued.