Question 2001Navigation General

The correct answer is B) all high waters. Mean high water is defined as the average height of all the high waters over a 19-year period. This is the standard reference plane used for navigation charts and other marine applications. The mean high water level represents the average of all the high tide heights, not just the lower or higher high tides. The other answer choices are incorrect because they do not accurately describe what mean high water represents. Option A refers only to the lower of the two daily tides, while options C and D refer to just the lower or higher high waters, respectively, rather than the average of all high waters.