The correct answer is option 2 - Ionosphere. The ionosphere is a layer of the Earth`s atmosphere that is located approximately 75-1000 kilometers above the Earth`s surface. It is composed partly of electrons and positive ions, which are created by solar radiation and cosmic rays interacting with the molecules in the atmosphere. These ions and electrons make the ionosphere electrically charged, allowing it to reflect and refract radio waves, making it important for long-distance radio communication. The ionosphere is also responsible for the occurrence of auroras in the polar regions, as charged particles from the solar wind interact with the ions and electrons in this layer.