Step 1: Casting Process Identification.
- Slush casting (II) is typically used for creating hollow statues, involving pouring molten metal into a mold and then removing the excess to leave a hollow form.
- Investment casting (IV) is employed for manufacturing dentures, known for its precision in creating small, complex components.
- Gravity die casting (I) is commonly used in the production of aluminum alloy pistons, well-suited for casting aluminum and similar metals.
- Shell moulding (III) is generally used for rocker arms, providing a good surface finish and accurate dimensions.
Step 2: Summary The correct matches are:
- (A) Hollow statues → (II) Slush casting
- (B) Dentures → (IV) Investment casting
- (C) Aluminum alloy pistons → (I) Gravity die casting
- (D) Rocker arms → (III) Shell moulding
Final Answer: \[ \boxed{(A) (I), (B) (II), (C) (IV), (D) (III)}\]