The correct answer is C) separate and accessible location. The reasoning for this is that according to Coast Guard regulations, each fireman's outfit and its spare equipment on a tankship must be stowed in a separate and accessible location, typically near the fire station or other designated fire safety equipment. This ensures that the firefighting gear is readily available and easy to retrieve in the event of an emergency, rather than being locked away or stored in an inconvenient location. The other answer choices are incorrect because: A) a fire hydrant location is not the designated storage area for firemen's outfits, B) the gear should not be locked away in the machinery space, and D) the gear should be stored in a separate, accessible location, not an unlocked cabinet in the machinery space.