A. Transmission line of length upto 600 km
B. Transmission line of length upto 500 km
C. Transmission line of length upto 200 km
D. Transmission line of length upto 80 km
Explanation: The transmission lines having length more than 80 Km and less than 200 Km are considered as medium transmission lines.Their operating voltage is more than short transmission lines but less than long transmission lines.