ANS:B - polystyrene

Disposable patterns, often used in foundry processes like investment casting or sand casting, are typically made of polystyrene. Polystyrene patterns are lightweight, easy to mold, and inexpensive to produce, making them ideal for creating intricate shapes quickly and efficiently. These patterns are formed by injecting molten polystyrene into a mold, which is then removed once solidified to leave behind the desired pattern. The patterns are then assembled into a cluster, often with a ceramic shell applied around them, before being subjected to the casting process. Once the metal has been poured and solidified, the polystyrene pattern is vaporized, leaving a cavity in the shape of the desired part. While patterns can be made from other materials such as metal, rubber, or wood, polystyrene is commonly used for disposable patterns due to its ease of use and cost-effectiveness.