The angle formed by the line of sight with the horizontal level when the point is below the horizontal level is called
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Angle of Depression
When an observer looks down at an object below the horizontal level through the eye, the angle between the line of sight and that horizontal level is the angle of depression. Looking up at an object above the horizontal level gives the angle of elevation instead.
Why the other options are incorrect
Option (1) Angle of Elevation — Incorrect. It is the angle with the horizontal when the object is above the horizontal level of the eye.
Option (2) Angle of Horizon — Incorrect. It is not a term used in heights and distances; the angles there are named only elevation and depression.
Option (4) Angle of Sight — Incorrect. The line of sight is the line from the eye to the object; its angle with the horizontal is named elevation or depression, not “angle of sight”.