Which of the following moulding techniques uses a sand and clay mixture as the mould material? 

Concept:

The moulding technique that uses a sand and clay mixture as the mould material is green sand moulding.

Explanation:

Green sand moulding is a commonly used technique in which a mixture of sand, clay, and water is used to create the mould for casting. The "green" in green sand refers to the fact that the sand mould is not "baked" or dried; it remains moist or "green."

Here are the key points for each moulding technique mentioned:

• Green sand moulding: Uses a mixture of sand, clay, and water.
• Shell moulding: Uses a resin-covered sand to form the mould.
• Investment casting: Uses a wax pattern covered with a refractory material to form the mould.
• Die casting: Uses metal moulds (dies) to cast metal parts under high pressure.

Therefore, the correct answer is:

1) Green sand moulding