I'll give you a question, please answer with step-by-step reasoning process.
The four equal sides were all a smooth surface, he had carved and sanded a perfect what?\nOptions:\n- lake\n- tetrahedron\n- ball\n- object\n- mirror

tetrahedron
Tetrahedron can be carved from a 4 equal side surface.

Smooth surface leads to carving of a perfect tetrahedron.

.

So, the final answer is tetrahedron