The correct answer is C. According to the regulations in 46 CFR, the fuel temperature limit control for automatic auxiliary boilers burning heavy fuel oil must be checked to ensure that it initiates a safety shutdown when the fuel temperature is lowered to a value below what is required for safe combustion. After the safety shutdown, a manual reset must be required before the boiler can be restarted. The other options are incorrect because they do not accurately reflect the regulatory requirements. Option A describes raising the fuel temperature above the safe level to initiate the shutdown, which is not correct. Option B describes the boiler restarting automatically after the shutdown, which is also not the requirement. Option D describes raising the fuel temperature to initiate the shutdown and automatic restart, which again does not match the regulations.