Final answer:
Elevation, also known as projection, is the angle above the horizontal plane used to specify the direction in a coordinate system and is necessary, alongside azimuth, to pinpoint a location in space. The correct option is 4.
Step-by-step explanation:
In geography, elevation refers to the angle above the horizontal plane at which you have to look up or down to see an object or a celestial body. This concept is also known as projection, which is correct for Option 4 in your choices. Elevation is used alongside azimuth to specify the direction in a coordinate system.
While azimuth (&) ranges from 0 to 360 degrees to cover all possible directions around the observer, elevation (A) ranges from +90 degrees (directly overhead, or the "zenith") to -90 degrees (directly below, or the "nadir").
When considering coordinates on the Earth or in space, one can use systems like latitude and longitude or declination and right ascension. These systems help identify a precise position on the surface of a sphere, such as the Earth or the celestial sphere. The correct option is 4.