Correct Option: C

A flight data recorder (FDR) is an electronic device employed to record any instructions sent to any electronic systems on an aircraft. Another kind of flight recorder is the cockpit voice recorder which records conversation in the cockpit, radio communications between the cockpit crew and others (including conversation with air traffic control personnel), as well as ambient sounds. Popularly referred to as a “black box” by the media, the data recorded by the FDR is used for accident investigation as well as for analyzing air safety issues, material degradation and engine performance.