Which of the following is true concerning the hose threads on compressed gas oxy- acetylene regulators and torches?

Correct Answer: Option D — The torch acetylene inlet hose thread connection is "left handed".

To prevent the accidental interchange of oxygen and fuel gas hoses, industry standards mandate that acetylene connections use left-handed threads, while oxygen connections use right-handed threads. This physical incompatibility is a critical safety feature designed to prevent the creation of explosive mixtures within the gas supply lines.