The correct answer is B) height of tide. The height of tide is the vertical distance from the tidal datum, which is a reference point for measuring tide levels, to the actual level of the water at a given time. This measurement represents the current height or elevation of the water relative to the tidal datum. The other options are incorrect because: A) Actual water depth refers to the vertical distance from the seafloor to the water surface, not the tidal datum. C) Range of tide is the difference in height between the high and low tides, not the height at a specific time. D) Charted depth is the depth of water shown on a nautical chart, which may not reflect the current water level.