The correct answer is A) The device labeled 'Generator Circuit Breaker' for that alternator should automatically open because of the reverse power relay. In the event of a turbine failure due to a throttle trip, the reverse power relay on the affected alternator's generator circuit breaker will detect the reverse power flow and automatically open the circuit breaker. This isolates the failed alternator from the electrical system, preventing it from drawing power from the remaining online alternator(s). The other options are incorrect because the emergency generator does not automatically start (B), the exciter does not drive the alternator on its own (C), and the operator does not need to manually open all generator circuit breakers (D) - the reverse power relay handles this automatically.