The correct answer is B) condensate drain system. High pressure and low pressure drain systems are part of the condensate drain system on vessels. The condensate drain system collects and routes condensed steam from various components, such as turbines, heat exchangers, and other steam-using equipment, back to the boiler or other water treatment systems. This closed-loop system helps conserve water and improve the overall efficiency of the vessel's steam plant. The other answer choices are incorrect because they do not accurately describe the systems that contain high and low pressure drains. The contaminated drain system, auxiliary turbine bleed system, and boiler drain system serve different functions on the vessel and do not typically include the high and low pressure drain components.