The correct answer is B) directly outside the space protected by the system. The controls for a fixed carbon dioxide system on uninspected vessels must be mounted directly outside the space protected by the system. This is in accordance with the regulations for fixed fire extinguishing systems on uninspected vessels, which require the controls to be located in an accessible position outside the space being protected. This ensures that the crew can easily access and activate the system in the event of a fire, without having to enter the endangered space. The other answer choices are incorrect because: A) the main deck near the bow may not be an accessible location, C) the pilothouse may be too far from the protected space, and D) mounting the controls near the gas cylinders does not provide the necessary accessibility for the crew.