B. protects the transmission line against direct lightning stroke C. supresses high frequency oscillation in the line D. reflects back the travelling wave approaching it Ans: A GS&EI ElectEngg 14 2024 1601-2025 Lightning arresters are protective devices that divert excess voltage surges to the ground, thus safeguarding equipment connected to the power system. They act as a switch that closes at a high voltage and opens when the surge has passed.