Which operation would best fit under the category of "editing" in GIS?

In the context of GIS, the category of "editing" primarily involves making modifications to spatial data and attributes to ensure accuracy and relevance. Correcting manual errors in features falls squarely within this realm, as it directly pertains to the actions taken to amend inaccuracies that may have occurred during data collection, input, or previous analysis. Editing is essential for maintaining the integrity of geographical information, enabling professionals to ensure that the data reflects the real-world conditions it is meant to represent.

The other options, while important aspects of GIS work, do not specifically encompass the editing function. Performing terrain analysis is related to evaluating and interpreting spatial data rather than modifying it. Exporting visual data refers to the process of saving map outputs or visual representations, which does not involve manipulating the data itself. Conducting data import processes focuses on bringing external data into the GIS environment rather than refining or correcting existing datasets. Thus, correcting manual errors in features is the operation that best embodies the editing activity within a GIS framework.