Question

Which is the relationship between photon energy and the color of light?

Answer 1

The energy of a photon is given by
$E=hf$
where 
h is the Planck constant
f is the frequency of the light.

From this formula, we see that the higher the frequency, the greater the energy, and viceversa.

Now let's have a look at the frequencies of the different colors of visible light. Violet is the color with higher frequency, while red is the color with lower frequency. This means that violet photons have the greatest energy, while red photons have the least amount of energy. So, correct answer is 

C. Red photons have the least amount of energy.