Explanation:
Absolute brightness is defined as the total amount of energy emitted from a celestial object. It is the brightness of a celestial object as seen by the observer on the earth.
Proto is a star that is very young. They are so dusty particles i.e. they are covered by dust such that they block the light that they emits.
Nebula consists of dust particles and some different types of gases. They are also known as star nurseries because new stars forms here.
Stars are the large balls of burning gas that give off light.
Hence, the correct match is :
Absolute brightness : The total amount of energy emitted from a celestial object
Proto : Star
Nebula : An interstellar cloud of dust and gases
Stars : Gigantic balls of burning gas that give off light
