The correct answer is A) High-pressure. The steam separator used with a steam whistle normally drains to the high-pressure drain system. This is because the steam whistle operates at a higher pressure than the main steam system, and the condensate from the steam separator needs to be routed to the high-pressure drain to maintain the proper pressure differential. The other options are incorrect because the low-pressure drain system handles lower-pressure drains, the contaminated drain system handles potentially hazardous drains, and the main turbine drain system is not associated with the steam whistle.