If humans cannot see ultraviolet waves, how can ultraviolet light be used to gather evidence of a crime?

Ultraviolet waves are invisible to human eyes, but they can make some substances fluoresce. Those substances absorb ultraviolet light and then emit visible light, which investigators can see and use to reveal evidence such as traces of bodily fluids. Therefore, the correct choice is “Ultraviolet light causes substances to fluoresce and give off visible light.”

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