C. longest wavelength
Explanation:
Photons with the lowest energy have the longest wavelength and the shortest frequency.
The energy of photons is given as:
E = hf = [tex]\frac{h c }{∧}[/tex]
where f is the frequency of photon
h is the planck's constant
∧ is wavelength
c is the speed of light
The more the frequency, the higher the energy of the photon.
Photons with low energy have long wavelength.
Learn more:
Wavelength https://brainly.com/question/6352445
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