Carrier current over the power line provides simultaneous tripping of circuit breakers at both ends of the line in one to three cycles.
Thereby high-speed fault clearing is obtained, which improves the power system stability.
The auto-reclosing simultaneous reclosing signal is sent thereby simultaneous (1 to 3 cycles) reclosing of the circuit breaker is obtained.
For simultaneous faults, carrier-current protection provides easy discrimination.
As per answer key "pilot protection" is true but there is mistake the right answer is "none".
EXAMIANS