A ship at anchor has been communicating marginally with a shore station approximately 200 miles distant on a frequency in the 4 MHz band periodically throughout the day. Toward the late afternoon and evening, what effect should be noticed?

Correct Answer: Option D — Communications should gradually improve and peak at night and early morning.

At 200 miles, the signal relies on ground wave or low-angle sky wave propagation. During the day, D-layer absorption attenuates the signal. As night approaches and the D-layer disappears, ionospheric absorption decreases significantly, allowing for better sky wave propagation and improved signal strength at the receiver during nighttime hours.