Question 1506 Deck General

The correct answer is C) They must be explosion-proof, self-contained, battery-fed lamps. This is correct because the use of portable electric lights in petroleum product tanks is strictly regulated to ensure safety. Explosion-proof, self-contained, battery-fed lamps are required to minimize the risk of ignition in these potentially hazardous environments. The other options are incorrect - option A is too restrictive, option B requires grounding which may not be feasible, and option D is not specific enough, as gas-free conditions may not always be maintained.