Correct Answer: Thermosphere

Solution : The correct answer is Thermosphere .

Radio transmission is aided by the thermosphere layer of the atmosphere. It exists above the mesosphere and beneath the exosphere. The temperature rises fast with increasing height in the thermosphere. This layer includes the ionosphere. This layer aids radio transmission, where radio waves emitted from the ground are reflected to the Earth. The International Space Station is housed in this layer while it orbits the Earth.