Circles cannot be converted to parcel segments. Parcel segments require defined start and end points (for lines and arcs) or a sequence of such endpoints along a boundary. A circle, being a closed curve with no endpoints, cannot be mapped to a single parcel segment. The tool can convert lines, polylines (into multiple segments along their vertices), and arcs (as curved segments between endpoints), but a circle would need to be approximated by multiple segments first.

In Civil 3D, the horizontal path is defined by an alignment and the vertical shape by a profile. When you combine those two, you get a single three-dimensional reference line that follows the centerline in plan and varies in elevation along the way. This integrated 3D representation is called a 3D chain. The term emphasizes the linked sequence of stations along the alignment with elevations from the profile, forming a continuous 3D path used to build corridors and generate sections and surfaces. While a curve or path could describe a line, they don’t inherently convey the tying together of horizontal and vertical geometry into one 3D entity, and a route is a more generic term.

In Civil 3D, selecting a parcel from the Prospector display area is done by clicking the parcel’s area label. The label is the user-facing handle tied to the parcel geometry, so tapping it highlights and selects that specific parcel in both the drawing and the Prospector. This approach is reliable when parcels are close together or share boundaries, because the label provides a clear target linked to the parcel data. The other actions don’t select a single parcel from the Prospector: clicking in empty space isn’t tied to any parcel, moving with the Move command starts a tool rather than selecting, and Delete removes objects rather than selecting them.

Defining the horizontal path of a linear feature in Civil 3D is done with an alignment—the 2D path made from straight lines, circular curves, and spiral transitions that traces the centerline of a road or similar feature. An alignment captures the plan view geometry, including tangents and curved sections, and can carry stationing information for design and labeling. Why this fits best: the description explicitly mentions a series of 2D lines, arcs, and spirals used to represent a linear feature in plan view, which is exactly how an alignment is defined in Civil 3D. It serves as the baseline geometry for other design elements, such as profiles (the vertical components along the alignment) and corridors (3D models built from the alignment, a profile, and an assembly). A profile, by contrast, represents elevation along the alignment rather than the horizontal path itself. A corridor uses the alignment as a path but is a 3D construct that combines the alignment, a profile, and an assembly to model pavement and other features. A surface represents the terrain surface, not the centerline or path geometry.