The correct answer is A. Sulphur.
Sulphur is the element that is used for vulcanizing rubber. Vulcanization is a process that makes rubber more durable and resistant to heat, cold, and chemicals. It is done by adding sulphur to rubber and then heating it. The sulphur reacts with the rubber to form cross-links between the polymer chains. This makes the rubber stronger and more elastic.
Bromine, silicon, and phosphorus are not used for vulcanizing rubber. Bromine is a halogen that is used to make flame retardants and other chemicals. Silicon is a metalloid that is used to make semiconductors and other materials. Phosphorus is a non-metal that is used to make fertilizers and other chemicals.
Sulphur is the only element that is used for vulcanizing rubber. It is a very effective way to make rubber more durable and resistant to heat, cold, and chemicals.