What is Dead Reckoning (DR), and what data are required to compute it?

What is Dead Reckoning (DR), and what data are required to compute it?

• A. DR is a method using only the current position and depth; required data are depth and tide.
• B. DR is a method of updating position using celestial sightings; required data are star positions and time.
• C. DR is an estimated position based on a known starting point, course over ground or heading, speed, and elapsed time; required data: last fix, course over ground or heading, speed, elapsed time, and currents/leeway.
• D. DR is the same as piloting; required data are landmarks.

Answer: (C)