Which of the following describes the corona?

The corona is indeed described as the outermost portion of the sun's atmosphere, characterized by its crown-like shape, which is where the name "corona" originates from, meaning "crown" in Latin. This layer extends millions of kilometers into space and is visible during a total solar eclipse as a halo of light surrounding the sun. It is much hotter than the layers below it, with temperatures reaching up to several million degrees Celsius. This unusual temperature in the corona is a subject of ongoing research, as it is hotter than the sun's surface, or photosphere, which is counterintuitive given standard thermal behavior. Understanding the corona's structure is essential in solar physics, as it plays a significant role in solar wind and solar flares that can impact space weather.