Which method is employed to align an unreferenced dataset to one with spatial reference information?

The correct choice is Georeferencing, which is the method used to align an unreferenced dataset with one that has spatial reference information. Georeferencing involves establishing a relationship between the unreferenced data and a coordinate system, allowing the unreferenced data to be accurately positioned in relation to known geographic coordinates.

By providing control points that correspond to known locations on the referenced dataset, georeferencing transforms the unreferenced data into a geospatial format that can be used in geographic information systems (GIS) or other spatial data analysis tools. This process is crucial because it allows analysts to overlay and integrate various datasets accurately, enabling meaningful insights and analysis that take advantage of the spatial relationships evident in the data.

In contrast, scaling refers to adjusting the size of an object in relation to a reference model, while defining projections involves specifying how a three-dimensional surface is represented on a two-dimensional plane without necessarily aligning unreferenced data. Reprojecting is the process of converting data from one coordinate system to another but assumes that the data is already georeferenced. Thus, georeferencing is the essential first step to make unreferenced datasets usable within a defined spatial framework.