What causes the maximum usable frequency to vary? A. The temperature of the ionosphere B. The speed of the winds in the upper atmosphere C. The type of weather just below the ionosphere D. The amount of radiation received from the sun

What causes the maximum usable frequency to vary?
A. The temperature of the ionosphere
B. The speed of the winds in the upper atmosphere
C. The type of weather just below the ionosphere
D. The amount of radiation received from the sun
by

1 Answer

Answer :

D. The amount of radiation received from the sun
by

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