Question 468Navigation General

The correct answer is D) soundings on the U.S. east and west coasts. Mean lower low water (MLLW) is the reference plane used for all soundings or water depth measurements on nautical charts for both the U.S. east and west coasts. This is the standard reference datum established by the National Oceanic and Atmospheric Administration (NOAA) for charting water depths. The other options are incorrect because: A) MLLW is not used for heights above water, B) it is used for both east and west coasts, not just the east coast, and C) it is specifically used for soundings/water depths, not all vertical measurements.