Your vessel has changed course and is heading 285°T, you are on the charted range and it appears as in illustration D048NG below. After several minutes the range appears as in illustration D047NG below and your heading is still 285°T. What does this indicate?

Correct Answer: Option D — north-setting current

When a range appears to open, the vessel is drifting off the range line. If the range markers shift such that the bottom marker moves to the right of the top marker, the vessel has been pushed to the north by a north-setting current, requiring a course correction.