The distance between any two meridians measured along a parallel of latitude and expressed in miles is the __________.

Correct Answer: Option A — departure

Departure is defined in Bowditch as the distance between two meridians at any given parallel of latitude, measured in nautical miles. It is distinct from difference in longitude, which is measured in degrees, and is calculated using the formula: Departure = Difference in Longitude × Cosine of the Mean Latitude.