The correct answer is D. stratosphere.
The stratosphere is the second major layer of Earth’s atmosphere, just above the troposphere and below the mesosphere. It is primarily made up of nitrogen and oxygen, and contains a layer of ozone (O3) in the upper part of the stratosphere, which absorbs most of the Sun’s ultraviolet radiation.
The ionosphere is a region of Earth’s atmosphere that is ionized by solar radiation. It is located in the upper atmosphere, from about 50 to 1000 kilometers above the Earth’s surface. The ionosphere is important for radio communications, as it reflects radio waves back to Earth.
The mesosphere is the third major layer of Earth’s atmosphere, just above the stratosphere and below the thermosphere. It is primarily made up of nitrogen and oxygen, and contains a layer of meteors that burn up as they enter the Earth’s atmosphere.
The thermosphere is the fourth major layer of Earth’s atmosphere, just above the mesosphere. It is primarily made up of hydrogen and helium, and contains a layer of plasma that is heated by the Sun’s radiation.