97J1 A
 A ship has been communicating effectively on 16 MHz during daylight hours with a shore station at a distance of 3500 miles. Toward late afternoon and evening what effect would be noticed?
A. Communications should gradually deteriorate and become impossible on this frequency at night.
B. Communications should be maintained with slight improvement in the signal received from the shore station.
C. The gray line effect will prevent communications after dark.
D. Communications should improve and peak at night.
