What function does the Extend command serve in a CAD environment?

The Extend command in a CAD environment is designed to lengthen lines or objects to meet or connect with other objects in the drawing. This function is particularly useful when you want to ensure that lines, edges, or surfaces precisely touch or intersect with other geometry without manually adjusting their lengths. By selecting the existing line and specifying the target object, the Extend command automatically modifies the existing object's length, effectively “adding” to it until it reaches the specified boundary.

In contrast, other options do not encapsulate the primary purpose of the Extend command. For instance, trimming lines to a specified length pertains to shortening existing lines rather than lengthening them. Creating new 3D features involves different commands and tools altogether, while modifying dimensions focuses on changing the measurement display or properties of already established dimensions, which does not involve extending the actual geometry.