Which description correctly defines a sphere?

Which description correctly defines a sphere?

• A. A perfectly round solid with no faces, edges, or vertices.
• B. A prism with six square faces.
• C. A solid with one curved surface and two congruent bases.
• D. A solid with six faces that are all squares.

Answer: (A)

A sphere is defined by being perfectly round all the way around, with no flat faces, no edges, and no vertices. This means every point on its surface is the same distance from a center point, creating a smooth, continuous curved surface. The description that says a perfectly round solid with no faces, edges, or vertices matches this idea exactly. The other descriptions point to different shapes: a solid with six square faces is a cube, which has edges and corners; a solid with one curved surface and two congruent bases is a cylinder, which has circular bases and a curved side; a solid with six faces that are all squares is also a cube.

A sphere is defined by being perfectly round all the way around, with no flat faces, no edges, and no vertices. This means every point on its surface is the same distance from a center point, creating a smooth, continuous curved surface. The description that says a perfectly round solid with no faces, edges, or vertices matches this idea exactly.

The other descriptions point to different shapes: a solid with six square faces is a cube, which has edges and corners; a solid with one curved surface and two congruent bases is a cylinder, which has circular bases and a curved side; a solid with six faces that are all squares is also a cube.