The angular distance of a heavenly body from the equator, measured along its meridian, is called A. Declination B. Altitude C. Zenith distance D. Co-latitude

The correct answer is: A. Declination

Declination is the angular distance of a celestial object from the celestial equator, measured along the hour circle passing through the object. Declination is positive north of the equator and negative south of the equator.

Altitude is the angle between the horizon and a celestial object. Zenith distance is the angle between the zenith and a celestial object. Co-latitude is the complement of latitude, or the angle between the zenith and the north pole.