A. Diamond, graphite and fullerene are the three crystalline forms of carbon.

1. A crystalline form has a definite and regular geometric pattern.

2. The structure of all the three crystalline forms has a definite shape, sharp edges and plane surfaces.

Graphite Diamond Fullerene

3. Graphite has a hexagonal layered structure.

4. Diamond has a tetragonal three-dimensional structure.

5. Fullerene exists in the form of buckyballs and buckytubes.