JEE Main 2021 Physics question

Two identical antennas mounted on identical towers are separated from each other by a distance of 45 km. What should nearly be the minimum height of receiving antenna to receive the signals in line of sight ? (Assume radius of earth is 6400 km)

• (A)19.77 m
• (B)39.55 mCorrect
• (C)79.1 m
• (D)158.2 m