Black phosphorus is the most stable allotrope of phosphorus. It has a layered structure. It is a very highly polymerised form of the element.
We can find black phosphorus in two main forms. They are alpha black phosphorus and beta black phosphorus.
While beta black phosphorus forms when white phosphorus is heated at 473K, alpha black phosphorus forms when we heat red phosphorus at 803K.
Beta black phosphorus conducts electricity while alpha black phosphorus doesn’t conduct electricity.
Hence, the correct option is C