The correct answer is B) Coal should be vented with surface ventilation only. This is correct because coal in bulk cargo can produce flammable and potentially explosive gases as it undergoes chemical reactions. To mitigate this hazard, the regulations require that coal cargoes be ventilated using surface ventilation only, rather than through ventilation, which could stir up and circulate the hazardous gases. The other options are incorrect - A) is incorrect because dunnage should not be placed against the ship's sides, as this could restrict airflow; C) is incorrect because through ventilation is not recommended for coal cargoes; and D) is incorrect, as wet coal can be loaded, but special precautions are required.