Final answer:
OPTION A,The shortest angular distance between two celestial objects as viewed from Earth is known as 'angular separation', measured in degrees.
Step-by-step explanation:
The shortest angular distance between two objects in the sky is known as angular separation. This is a measurement of the angle formed at an observer's eye by two celestial objects as if they were connected by an imaginary line. Astronomers measure angular separation using degrees as a unit of measure, where a full circle around the celestial sphere constitutes 360°.
For instance, if two stars appeared 18° apart in the night sky, they would span approximately 1/10 of the sky's dome from the observer's perspective. It's also worth noting that the full Moon roughly measures half a degree in angular size, providing a tangible example of how astronomers gauge distances in the sky.
Declination, on the other hand, is an angular measurement north or south of the celestial equator, akin to latitude on Earth. It is not used to measure the distance between two objects, but rather the position of a single object relative to the celestial equator.