In geometric modeling, spline curves are used for:

Correct Answer: B – Complex surfaces
Explanation:
In geometric modeling, spline curves are mathematical curves used to represent smooth and flexible shapes, making them ideal for complex surfaces like car bodies, aircraft fuselages, and product designs. Unlike straight edges (A), rectangles (C), or simple polygons (D), spline curves can precisely model curved and free-form geometries. Common spline types include B-splines, Bézier curves, and NURBS, which allow designers to control curvature and surface continuity. They are essential in CAD (Computer-Aided Design), animation, and industrial design for creating realistic, smooth, and adjustable 2D and 3D shapes.