What characteristic defines "completely contain" in GIS?

The characteristic that defines "completely contain" in GIS is that each point of the source feature must fall inside the target feature. This definition highlights the idea that for one feature (the source) to be considered as completely contained within another feature (the target), every single part of the source must lie within the boundaries of the target.

This is particularly important for spatial analyses and operations in GIS, as it dictates how features interact and relate to each other geographically. The concept is widely used in various analyses, such as determining land use, habitat mapping, and more where spatial relationships of features play a crucial role.

The other options do not accurately capture the essence of "completely contain." For instance, the notion that only overlapping boundaries matter does not ensure that the entire source feature is inside the target. Having equal area is irrelevant to the concept of containment, as one feature can be significantly larger than the other while still being completely contained. Lastly, the concept of "completely contain" applies not just to polygons but can also be relevant for points and lines, depending on the context and the geometries involved.