Answer:
Low energy
Step-by-step explanation:
The energy of the light is directly proportional to its frequency, according to the relationship:

where
h is the Planck constant
f is the frequency of the radiation
In the visible light part of the spectrum, red light is the radiation with lowest frequency (while blue and violet are the radiation with highest frequency), therefore it is also the light with lowest energy. Therefore, it is used in the dark rooms, in order to cause the least damage to the films.