Step 1: Determine the requirement for a "strong abrasive" for stone. To effectively smooth or shape stone, a material considerably harder than the stone itself is necessary.
Step 2: Assess the available choices. Softstone, Limestone, and Sandstone are types of rock, not specialized abrasives. Carborundum, commonly known as Silicon Carbide (SiC), is an exceptionally hard synthetic compound, nearly as hard as diamond on the Mohs scale. It is commonly employed for grinding, sanding, and polishing hard materials such as stone and metal.