The "short rules" of propagation necessary to select the appropriate frequency band are:

Correct Answer: Option C — Shorter distance = Lower Frequency, Daytime = Higher Frequency.

Ionospheric propagation dictates that higher frequencies are required during daylight hours due to increased ionization of the D-layer, which absorbs lower frequencies. Conversely, shorter distances require lower frequencies, as higher frequencies may skip over the target area, failing to reflect back to the receiver within the desired range.