Damn Yutaka! You’re a genius!

(here the translation of the ENEM(National High School Exam) weird question:
Our skin have cells that reacts due the effect of ultraviolet light, and they produce a substance called melanin, that is responsible for the skin pigmentation. Thinking about tanning her self, a girl dressed a bikini, turned on the room light and lay exactly under the bright light. After many hours she realized that didn’t get any result.
The tanning process didn’t happen because the lamp light bright is:
A: Low intensity
B:Low frequency.
C:A continuous spectrum.
D: Inadequate amplitude.
E: Short length wave.)