Final answer:
Class B fires involve flammable liquids, gases, and certain other substances, but not ordinary combustibles, which characterize Class A fires.
Step-by-step explanation:
All of the following are characteristics of Class B fires, except:
- Involving flammable liquids
- Involving gases
- Involving combustible metals
- Involving ordinary combustibles
The correct answer is d. Involving ordinary combustibles. Class B fires specifically involve flammable liquids such as gasoline, gases like propane, or substances that can create fires under specific conditions such as ignitable compressed gases and oxidizers. However, they do not include fires involving ordinary combustibles like wood, paper, and fabric, which are characteristics of Class A fires.