What is the lowest temperature at which the vapors of a flammable liquid will ignite and cause self-sustained combustion in the presence of a spark or flame?

Correct Answer: Option A — fire point

The fire point is defined under 46 CFR and NFPA standards as the lowest temperature at which sustained combustion of flammable liquid vapors occurs following ignition, distinguishing it from the lower flash point where only momentary flashing happens.