Final answer:
Declination measures the angular distance of an object north or south of the celestial equator, like how latitude is measured on Earth.
Step-by-step explanation:
The declination of an object in the sky refers to its angular distance north or south of the celestial equator. Declination is similar to how latitude is measured on Earth, but instead of being relative to the terrestrial equator, it is measured relative to Earth's celestial equator on the celestial sphere. An object at the north celestial pole has a declination of +90°, while an object at the south celestial pole has a declination of -90°. For an object on the celestial equator, the declination is 0°. Therefore, the correct answer to the student's question is that declination measures an object's angular distance from the celestial equator, aligning with option "A. its angular distance from the celestial equator."