The outermost layer of the sun is called.

The Sun's atmosphere is composed of several layers, mainly the photosphere, the chromosphere, and the corona. It is in these outer layers that the energy of the Sun, which has sprung from the inner layers of the Sun, is detected as sunlight.

The lowest layer of the solar atmosphere is the photosphere. It is in this layer that solar energy is released in the form of light.

The next layer is the chromosphere. The chromosphere emits a reddish glow as super-heated hydrogen burns off.

The third layer of the solar atmosphere is the corona. It appears as white streamers or plumes of ionized gas that flow outward into space.

The correct option is D: Corona