Which three-dimensional figure has a polygon base and triangular faces meeting at a common apex?

• A. Cube
• B. Sphere
• C. Cone
• D. Pyramid

Answer: (D)

A three-dimensional figure with a polygon base and triangular faces meeting at a single top point is a pyramid. The base can be any polygon (triangle, square, pentagon, etc.), and from each edge of the base, a flat triangle rises so that all those triangles share the same apex above the base. This creates a solid with one polygonal base and several triangular side faces that converge at the apex. For example, a square base gives a pyramid with four triangular sides, while a triangular base gives a tetrahedron.

This differs from a cube, which has square faces and no single apex where all faces meet; a cone, which has a circular base and curved lateral surface; and a sphere, which has no faces at all.