Final answer:
A shape with one flat surface that can be traced to form a circle and one vertex is a cone.
Step-by-step explanation:
The shape described has one flat surface and one vertex, and the flat surface can be traced to make a circle. The shape that matches this description is a cone. A cone has a circular base (the flat surface), which can be traced to form a circle, and it comes to a single point, known as the vertex. In contrast, a cube has six flat surfaces and eight vertices, a cylinder has two flat surfaces and no vertices, and a sphere has no flat surfaces or vertices at all.