Correct Answer - Option 2 : direction theodolite
A directional theodolite has only one vertical axis, and a single horizontal clamp-and-tangent screw which controls the rotation about the vertical axis.
Theodolite is a surveying instrument used in measuring horizontal and vertical angles.
The various types of Theodolite are specified below:
Transit Theodolite: A theodolite is named a transit theodolite once its telescope will be transited i.e. rotated through a whole revolution regarding its horizontal axis within the vertical plane.
Non-Transit Theodolite In this kind, the telescope cannot be transited.
Total Station: The total Station accommodates the functions of a theodolite for measuring angles, an EDM for measuring gaps, digital data, and information documentation.
Directional Theodolite: Angles are obtained by deducting the first direction reading from the second direction reading. This reads directions rather than angles. The common usage of direction theodolite is in triangulation.
Repeating Theodolite: Repeating theodolites are theodolites that measure angles on a graduated scale. The average of the angle measured is then derived. This is done by dividing the total of these readings by the number of readings that were taken. It is used in locations where the base is not steady.