Basic Qualification · B-007 Radio wave propagation · B-007-002-003
Which ionospheric region is closest to the Earth?
- AThe F region
- BThe A region
- CThe D region
- DThe E region
Correct answer: C — The D region. From the official ISED question bank, verified word for word.
Why
The D region is the correct answer because it forms the lowest layer of the ionosphere, sitting between 60 and 90 kilometres above the ground, making it the closest to Earth. The full explanation — and one for every question — is in Pro.
Practise this section
Radio wave propagation is section B-007 of the Basic exam: How signals travel: the ionosphere and its layers, skip, ground wave, sporadic E, and which bands work when.
Drill B-007 — free, no account