Rapid flutter on mobile signals due to multipath propagation✓Correct answer
A type of ground system used with vertical antennas
Interference from cable TV in the form of carriers at fixed intervals across the band
Explanation
Picket fencing is the rapid fluttering heard from a moving station, caused by the vehicle passing quickly through the alternating reinforcement and cancellation zones of a multipath field. The name comes from the sound resembling something being dragged along a picket fence.