Question

on the torch body, turn off the — valve first to put out the flame.
select one:
a. acetylene
b. turn off oxygen and acetylene valves at the same time
c. you should close cylinder valves to allow gas in hoses to be burnt
d. oxygen

Explanation:

When turning off the valves on a torch body to put out the flame, the acetylene valve is turned off first. This is because acetylene is a fuel gas, and turning it off first helps prevent the formation of a back - fire or flashback situation. If oxygen is turned off first, unburned acetylene can accumulate in the system, which is a safety hazard.

Answer:

A. Acetylene