The correct answer is C) Continue loading, as this is a normal procedure. The reasoning is that the inert gas system is not required to be in operation during the loading of crude oil on a tank vessel, as long as the oxygen content in the cargo tank remains below 16%. Continuing the loading operation without the inert gas system running is considered a normal procedure, as long as the oxygen levels are monitored and maintained within the acceptable range. Option A is incorrect because the inert gas system is not required to be started up until the oxygen content reaches 8%. Option B is incorrect because stopping the loading operation is not necessary if the oxygen levels are within the acceptable range. Option D is incorrect because there is no need to operate under "Emergency Procedures" if the oxygen levels are being properly monitored and maintained.