Luminosity is the amount of light a star directly emits from its surface.
Luminosity is a measure of the amount of light a star directly emits.
Answer : Option A
Light intensity is similar to brightness of the light where it is a measure of amount of light focused with respect to area and its unit is called as lux represented by lx.
Different light has different wavelengths according to the electromagnetic spectrum. Luminosity is the best option from the given ones as is a measure of amount of light emitted from an object which is here referred to a star.
Luminosity is defined as the amount of energy per unit of time emitted in all directions by a celestial body (a star).
Taking into account that all stars radiate light in a wide range of frequencies (or wavelengths) of the electromagnetic spectrum, this value is directly related to the absolute magnitude of the star and depends on its temperature and its area.