Which of the following statements about fire-gas detectors is MOST accurate?

A. Fire-gas detectors are also called visible products-of-combustion detectors.
B. Fire-gas detectors initiate alarm signals faster than any other type of detector.
C. Fire-gas detectors can be designed to be sensitive to only gases produced by hostile fires.
D. For general detection, fire-gas detectors monitor levels of hydrogen chloride and hydrogen cyanide in the air.

C