Towing vessel fire protection regulations require that all fuel tank vent pipes comply with all of the following provisions EXCEPT that the vent _______________ .

A
connects to the highest point of the tank
B
system discharges on a weather deck through a U-shaped 180 degree pipe bend
C
be fitted with a 30-by-30 corrosion resistant flame screen
D
must have a positive-acting shut-off valve to prevent water from entering the tank in heavy weather
E