Which of the following procedures would be correct when first lighting-off an oxyacetylene torch?

Correct Answer: Option A — Open the acetylene valve very slightly to light-off and then open and adjust the oxygen valve.

Safety protocols for oxyacetylene torches dictate opening the acetylene valve slightly first to establish a flame, then introducing oxygen. This sequence prevents the oxygen-rich environment from causing a flashback or an uncontrolled flare-up, ensuring the flame is stable before adjusting the mixture for the desired heat.