Final answer:
The full moon has an apparent magnitude of around -12, making it quite bright in the night sky when compared to other celestial bodies.
Step-by-step explanation:
The full moon has an apparent magnitude of roughly -12. The apparent magnitude scale is used in astronomy to measure the brightness of celestial objects as seen from Earth. A lower number indicates a brighter object, with negative numbers being the brightest. For instance, the Sun has an approximate magnitude of -26.7, making it the brightest object in our sky. Therefore, the correct answer to the student's question is option d. -12. The brightness of an object in the sky varies with its distance from the observer and its intrinsic luminosity. The Moon, being our closest celestial neighbor, is quite bright in the night sky when it's full, although it is vastly outshone by the Sun.