The correct answer is A) by transmitter. The indications of the master gyrocompass are sent to remote repeaters by a transmitter. The transmitter takes the data from the gyrocompass and converts it into an electrical signal that can be sent to other locations, such as remote repeater compasses, to display the same heading information. This is the standard method for communicating gyrocompass data to remote locations on a vessel. The other options are incorrect because: B) a phantom element is not used to transmit gyrocompass data, C) a follow-up system is used to maintain the gyrocompass's orientation, not to send data to repeaters, and D) an azimuth motor is used to rotate the gyrocompass, not to transmit its indications.