Final answer:
The correct answer is option D) Near a busy exit.
Step-by-step explanation:
The question relates to the safe storage conditions for gas cylinders inside buildings. The correct conditions for storing gas cylinders include ensuring that they are in a well-ventilated area, away from heat sources, and secured in an upright position.
However, storing them near a busy exit does not meet safety conditions as it can lead to obstructions and hazards during an emergency evacuation. Cylinders must be kept in a location that won't impede escape routes or exits.