Correct Answer:
C. Ship
Explanation:
A knot is a specialized non-SI unit utilized internationally for measuring speed in maritime navigation and meteorology/aviation.
Important Facts:
• Value: One knot is equal to one nautical mile per hour, which is exactly 1.852 km/h (approx. 1.15 mph).
• Historical Origin: Sailors used to throw a log tied to a knotted rope into the sea and counted how many knots passed through their hands in a fixed time measured with an hourglass.
• Primary Application: It is mainly used for ships, boats, submarines, and aircraft speed measurement.