As shown in the figure, a 12.2 m high tree is an obstacle on a 10 km point-to-point communication link. The distance between the tree and one of the antennas is 4 km.
If the signal transmission frequency is 5.8 GHz, what is the minimum installation height of the receive and transmit antennas based on the following formula and the Fresnel zone radius at the 4 km point?
A . 16 m
B . 19 m
C . 22 m
D . 26 m
Answer: B