Answer:
Blues
Step-by-step explanation:
Colors of Rainbow => ROYGBIV
Red Orange Yellow Green Blue Indigo Violet
low energy => => => => => => => => => => high energy
low frequency => => => => => => => => => high frequency
long wavelengths => => => => => => => => short wavelengths
Note: All L's on the Left => low, low, long; other end are opposites.