Answer:
The correct answer would be b. corona.
The surface feature of the sun includes solar prominences, sunspots, solar flares, and coronal mass ejections (CME's).
Corona refers to the aura of plasma that is present around the stars including sun.
The sun's corona can be seen only during a total solar eclipse when it is seen in the irregular form which appears very shiny like a pearl which surrounds the dark disk of the moon.
