You are steaming in a westerly direction along the Gulf Coast. You see ahead of you a lighted buoy showing a red isophase light. Which action should you take?

Correct Answer: Option B — Alter course to port and leave the buoy to starboard.

Steaming westerly along the Gulf Coast constitutes proceeding from seaward into local waters under IALA-B. Red isophase lights designate the starboard channel boundary; therefore, the navigator must alter course to port to leave the red buoy to starboard.