What AutoCAD command is used to create smooth curves?

The command used to create smooth curves in AutoCAD is the Spline command. This command allows users to define complex curves through control points, which helps to create fluid and aesthetically pleasing shapes. Unlike other options, the Spline provides a higher degree of flexibility in designing non-linear paths or shapes, making it ideal for applications requiring intricate designs and smooth transitions.

The Spline can be defined by specifying points along the curve, which AutoCAD uses to interpolate the smooth transition between these points. This makes it particularly useful for creating organic shapes or detailed outlines that can't be easily achieved with other geometric shapes.

In contrast, while the Arc command is limited to creating predefined sections of circles, and the Bezier command is powerful for vector graphic applications but is not as commonly utilized in standard AutoCAD work, the Spline's functionality is specifically tailored for smooth, flowing curves. The Circle command, while it creates a perfect round shape, lacks the ability to generate smooth curves in a freeform manner. Thus, the Spline command stands out as the correct choice for creating smooth curves in AutoCAD.