The correct answer is C) declination. The arc of an hour circle between the celestial equator and a point on the celestial sphere, measured northward or southward through 90°, is the declination of that point. Declination is the angular distance of a celestial body north or south of the celestial equator, and it is one of the fundamental coordinates used to locate objects in the celestial sphere. The other options are incorrect because latitude is the angular distance of a point north or south of the Earth's equator, azimuth angle is the horizontal angle of a celestial body measured clockwise from the north point of the horizon, and altitude is the angular distance of a celestial body above the horizon.