Which operation extracts input features that are within specified clip features?

The operation that extracts input features which fall within specified clip features is known as "Clip." This process involves using a polygon (the clip feature) to define an area of interest, within which parts of the input features will be retained. All parts of the input features that lie outside the boundaries of the clip feature are discarded.

Clipping is particularly useful in GIS for creating a more manageable dataset focused on a specific area, allowing for analysis or visualization without the distraction of surrounding or irrelevant data. By using clip functions, users can effectively isolate geographic data that pertains directly to their study area.

The other options represent different spatial operations: "Intersect" combines features where they overlap, while "Erase" removes portions of input features that overlap with the erase features. "Buffer" creates areas around features at a specified distance but does not extract features. Thus, "Clip" is the most accurate term for the operation described in the question.