Descriptive geometry and CAD graphics: identify the surface type that can appear as a true plane, as a single-curved form (such as a cylinder or cone), or as a warped (doubly curved) surface depending on how its generators are arranged.

Introduction / Context:
In descriptive geometry and computer-aided design (CAD), surfaces are often classified by how they are generated. A particularly versatile class is the ruled surface, created by sweeping a straight line (called a generator) along two guiding curves. Depending on the guides, the result may be planar, simply curved, or even warped.

Given Data / Assumptions:

• The question contrasts plane, single-curved, and warped surfaces.
• We assume standard drafting terminology: generator, directrix, developable vs. non-developable surfaces.
• We seek the surface category that encompasses all three manifestations.

Concept / Approach:
A ruled surface is defined by the motion of a straight line. If the generator remains coplanar, the surface is a plane. If the generator stays tangent to a fixed direction around a curve (for example, cones and cylinders), the surface is single-curved and developable. If the generator twists between skew guides (for example, a hyperbolic paraboloid or a helicoid), the surface becomes warped (doubly curved and typically non-developable).

Step-by-Step Solution:

Verification / Alternative check:
Open a CAD modeler and create surfaces using a line swept between two rails. By changing rail geometry from coplanar, to circular/linear, to skew pair, you can observe plane, single-curved, and warped outcomes respectively—all ruled.

Why Other Options Are Wrong:

• Edge surface: Not a standard surface class; edges are boundaries.
• Auxiliary surface: Refers to a construction concept, not a generative class.
• Developed surface: Not all ruled surfaces are developable (warped surfaces are not).

Common Pitfalls:
Confusing “ruled” with “developable.” Many ruled surfaces are developable, but warped ruled surfaces are not.

Final Answer:
Ruled surface