The correct answer is B) Where they pass through watertight bulkheads, they should be fitted with watertight stuffing boxes. This is the correct answer because electrical cables passing through watertight bulkheads must be fitted with watertight fittings, such as stuffing boxes, to maintain the integrity of the watertight boundary. This is a requirement specified in regulations to ensure the watertight integrity of the vessel's structure. The other options are incorrect because: A) Electric cable coverings should be grounded as per electrical safety standards, C) Electrical cables are typically secured in place using cable ties or clips, not glued, and D) Electrical cables are not required to be welded in place, as this would be an overly restrictive and impractical installation method.