Your vessel receives a distress call from a vessel reporting her position as LAT 35°01'S, LONG 18°51'W. Your position is LAT 30°18'S, LONG 21°42'W. Determine the true course from your vessel to the vessel in distress by Mercator sailing.

Correct Answer: Option B — 153°T

Mercator sailing formulas utilize difference in latitude, difference in longitude, and meridional parts to compute true course between positions. Applying these navigational mathematics yields a true course of 153°T between the specified Southern Hemisphere coordinates.