A vessel is steaming in east longitude on January 25 and crosses the International Date Line on an eastbound course at 0900 zone time. What is the date and time at Greenwich when the vessel crosses the line?

Correct Answer: Option B — 2100, 24 January

In USCG General Navigation principles (Bowditch, Light Lists, and Coast Pilots), regarding 'A vessel is steaming in east longitude on January 25 and crosses the International Date Line on an eastbound course at 0900 zone time. What is the date and time at Greenwich when the vessel crosses the line', the verified fact is: '2100, 24 January'.