If emergency welding repairs must be made to the upper area of a fuel tank, the tank and/or adjacent compartments may need to be __________.

Correct Answer: Option D — all of the above as necessary

Hot work on fuel tanks requires eliminating all ignition sources and flammable vapors. Depending on the specific tank configuration and the nature of the repair, filling with water, gas-freeing, or inerting are standard safety measures used to ensure the environment remains non-combustible throughout the duration of the welding process.