Q: Fact 1: Alaser is used for producing light. Fact 2: Light reveals what lies hidden in darkness. Given the two facts above, what can be used to reveal what lies hidden in darkness?

Available choices:
I. A laser;
II. Night;
III. photons;
IV. energy;
V. Electrical;
VI. Blackness;
VII. heat;
VIII. Hidden health issues;
The answer is:
I.