3. What is the definition of a pyramid?

(A) A pyramid is a polyhedron with two parallel faces that are identical copies of each other, called bases, connected by rectangles.
(B) A pyramid is a polygon with three straight sides and three vertices.
(C) A pyramid is a polyhedron that has one special face called the base, and all the other faces are triangles that meet at a single vertex.
(D) A pyramid is a polygon with 4 straight sides and four vertices.