GATE MT 2020 Q33.

Correct answer is option D. mortal_jaisu desribed it best. Thank you.

Some peripheral lines related to this topic:

• Sand casting, also known as sand moulded casting, is a metal casting process characterised by using sand as the mould material.
• Moulds made of sand are relatively cheap, and sufficiently refractory even for steel foundry use.
•  In addition to the sand, a suitable bonding agent (usually clay) is mixed or occurs with the sand. The mixture is moistened, typically with water, but sometimes with other substances, to develop the strength and plasticity of the clay and to make the aggregate suitable for moulding.
• Th powder metallurgy press and sinter process generally consists of three basic steps: powder blending (pulverisation), die compaction, and sintering.
• Compaction is generally performed at room temperature, and the elevated-temperature process of sintering is usually conducted at atmospheric pressure and under carefully controlled atmosphere composition.
• Optional secondary processing such as coining or heat treatment often follows to obtain special properties or enhanced precision.
• Wire drawing is a metalworking process used to reduce the cross-section of a wire by pulling the wire through a single, or series of, drawing die(s).
• There are many applications for wire drawing, including electrical wiring, cables, tension-loaded structural components, springs, paper clips, spokes for wheels, and stringed musical instruments.
• In investment casting,the material is poured into a cavity in a refractory material that is an exact duplicate of the desired part.
• Due to the hardness of refractory materials used, investment casting can produce products with exceptional surface qualities, which can reduce the need for secondary machine processes.
• In extrusion, a material is pushed through a die of the desired cross-section.
• The two main advantages of this process over other manufacturing processes are its ability to create very complex cross-sections, and to work materials that are brittle, because the material only encounters compressive  and shear stresses.
• It also forms parts with an excellent surface finish.