What are the two common categories of onboard oxygen systems used in aircraft, and one safety concern for each?

• A. Gaseous oxygen systems (continuous flow or demand) with fire/pressure hazards; chemical oxygen generators (emergency masks) with heat and caustic residue hazards.
• B. Liquid oxygen systems with cryogenic hazards; chemical oxygen generators (emergency masks) with heat hazards.
• C. Gaseous oxygen systems with no hazards; chemical oxygen generators with no hazards.
• D. Compressed air systems used for oxygen supply.

Answer: (B)