A ship is in longitude 54°00'W on a true course of 090°. The ship's clocks are on the proper time zone. At what longitude should the clocks be changed to maintain the proper zone time?

Correct Answer: Option C — 52°30'W

A ship traveling eastward on course 090 degrees from longitude 54 degrees West crosses into the next time zone boundary when reaching 52 degrees 30 minutes West. Time zone boundaries are established every 15 degrees, with zone changes occurring at the 7.5-degree intermediate meridians per Bowditch.