What are two possible reasons for features shifting in a GIS project?

The choice of a new dataset being assigned the wrong projected coordinate system is a valid reason for features shifting within a GIS project. When data layers are projected into a coordinate system, and any one of those datasets uses an incorrect coordinate system, it can lead to misalignment with other datasets that use the correct system. This misalignment occurs because the geometries of the features will be interpreted in a way that does not accurately reflect their intended location on the Earth's surface. As a result, they will appear shifted relative to other layers in the map.

By ensuring that all datasets used in a project are assigned the correct projected coordinate system, and by double-checking their source and the context in which they were collected, you can minimize this issue and maintain spatial accuracy across the GIS layers. This understanding is critical for users of GIS who need to overlay various data and perform spatial analyses.

While other reasons, such as random error from on-the-fly projection or inappropriate geographic transformations, can also cause shifts, the choice specifically addresses a straightforward and common instance of incorrect assignment leading to spatial discrepancies.