Answer : Amongst the given choices a weak beam of ultraviolet light is considered to be the worst as compared to others.
The wavelength of UV light is from 10 nm to 400 nm, and its energy varies from 3 eV to 124 eV.
As a single beam of UV light will have much energy in each photon which is emitted. The damage done by UV rays is observed to be very harmful in human cells and may cause many diseases. UV rays can also damage the eyes as more than 99% of UV radiation is absorbed by the front of the eyes. It can also lead to ultimate blindness. Therefore, it is considered to be much worse than an intense beam of infrared light.