The correct answer is A. Sulphur.
Vulcanization is a chemical process that converts natural rubber or related materials into more durable products. The process involves heating rubber with sulfur, which causes the rubber to cross-link and become stronger and more resistant to heat, cold, and abrasion.
Sulphur is the most common element used for vulcanization, but other elements such as chlorine, bromine, and phosphorus can also be used. The type of element used will affect the properties of the vulcanized rubber. For example, rubber vulcanized with sulphur is more resistant to heat and cold, while rubber vulcanized with chlorine is more resistant to abrasion.
The vulcanization process is typically carried out in a series of steps. The first step is to mix the rubber with sulfur and other additives. The mixture is then heated to a high temperature, which causes the sulfur to react with the rubber and form cross-links. The final step is to cool the rubber, which sets the cross-links and forms the final product.
Vulcanization is a critical process in the production of many rubber products, including tires, hoses, and gaskets. It is also used to produce other materials such as neoprene and butyl rubber.