A sailing vessel with the wind on her port side observes another sailing vessel to windward but cannot determine with certainty whether that vessel has the wind on her port or starboard side. What action is required of the port-wind vessel?

1. A. She may maintain course and speed until the other vessel's tack is confirmed
2. ✓ She shall keep out of the way of the other vesselCorrect
3. C. She shall sound one short blast and alter course to starboard
4. D. She shall exhibit a conical shape to indicate her uncertainty