Which of the following tools is primarily used to measure angles in surveying?

The theodolite is a precision instrument specifically designed for measuring angles in both horizontal and vertical planes. It consists of a movable telescope mounted on a tripod, allowing surveyors to determine angular measurements with high accuracy. The theodolite is essential for various surveying applications, including construction, land division, and topographical surveys, as it helps in establishing points and lines based on angle measurements.

Other tools mentioned serve different purposes: a measuring wheel is typically used for distance measurement along a surface, a surveying tape is used for linear distance measurements, and a GPS unit primarily provides geographic positioning and does not directly measure angles. The unique capability of the theodolite to offer precise angular measurements makes it the tool of choice for surveying tasks that require such data.