Why is skip propagation via the F2 region longer than that via the other ionospheric regions?
Because it is the densest
Because of the Doppler effect
Because it is the highest✓Correct answer
Because of temperature inversions
Explanation
F2 is the highest of the ionospheric regions, so a ray launched at a given low takeoff angle travels much farther before its downward-curving path reaches the ground. Density is a tempting answer since F2 is indeed the densest region, but density sets the highest usable frequency, not the length of a hop.