AOzonosphere
BMesosphere
CExosphere
DIonosphere
Answer:
D. Ionosphere
Read Explanation:
Long-distance radio communication is made possible through the thermosphere by the presence of the ionosphere.
The ionosphere is a layer of the Earth's atmosphere, primarily located within the thermosphere (and extending into the mesosphere). It contains a high concentration of ionized particles (electrons and positively charged ions), which can reflect radio waves back to Earth. This property is especially important for long-distance radio communication because it allows radio waves to travel beyond the line of sight and cover much larger distances, making communication possible over vast areas.
In particular, high-frequency (HF) radio waves are reflected by the ionosphere, enabling amateur radio operators, aviation communication, and international broadcasts to occur over long distances without the need for satellite systems or other technologies.