Final answer:
The subcategories of fusion welding are TIG Welding, MIG Welding, and Plasma Welding. The heat sources used in fusion welding include tungsten electrode, consumable wire electrode, and plasma arc.
Step-by-step explanation:
Fusion welding is a method of joining metal materials by using heat and solder. There are several subcategories of fusion welding. The correct answer is option C: TIG Welding, MIG Welding, and Plasma Welding. These subcategories use different techniques and equipment to achieve the fusion welding process.
The heat sources used in fusion welding vary depending on the welding method. TIG Welding (Tungsten Inert Gas Welding) uses a tungsten electrode and a constant current power supply. MIG Welding (Metal Inert Gas Welding) uses a consumable wire electrode and a shielding gas. Plasma Welding uses a plasma arc as the heat source.