9-45F4 D
 What are the principles of operation of a fiber-optic gyro compass?
A. A fiber-optic coil and three accelerometers determine the speed of rotation of the earth.
B. Two fiber-optic coils with one accelerometer and a level sensor determine the direction of true north. 
C. Three fiber-optic coils with a dual accelerometer and a yaw detector determines the direction of true north.
D. Three fiber-optic coils and a dual-axis electronic level sensor determine the direction of true north.
