Which three-dimensional figure has nine edges?

A triangular prism has two triangular faces, each with 3 edges, plus 3 edges joining the matching vertices of the triangles. That gives 3 + 3 + 3 = 9 edges, so the correct choice is the triangular prism. A rectangular pyramid has 8 edges, a triangular pyramid has 6, and a rectangular prism has 12.

AI-written and checked against the verified answer.