The correct option is 1.6 km.
Explanation
A Statute mile is a standard unit of length in the Imperial and US customary systems, primarily used for measuring distances on land. It is distinct from the Nautical mile, which is used for maritime and aerial navigation.Detailed Analysis:
- Statute Mile: It is legally defined as 5,280 feet or 1,760 yards. When converted to the metric system, 1 Statute mile equals approximately 1.60934 kilometers. For general purposes, this is rounded to 1.6 km.
- Comparison with Nautical Mile: A Nautical mile is based on the circumference of the Earth (equal to one minute of latitude) and is exactly 1.852 km (often rounded to 1.8 km). This explains 1.8 km.
- Context of 21.9 km: 21.9 km is approximately equal to 12 Nautical miles (22.2 km), which is the limit of the Territorial Sea from the baseline under the United Nations Convention on the Law of the Sea (UNCLOS).
Key Takeaway:
One Statute mile (used on land) is approximately 1.6 km, whereas one Nautical mile (used at sea) is approximately 1.85 km.