The correct option is Red clay.
Explanation
The pottery of the Indus Valley Civilization (Harappan Civilization) is a distinct marker of its material culture. It is predominantly wheel-made, with hand-made examples being rare, and is characterized by specific firing techniques and surface treatments.
Analysis:
- Primary Material: The typical plain pottery found across Harappan sites is primarily made of fine red clay.
- Appearance: Upon firing in a kiln, the clay assumes a characteristic red or pinkish colour. This forms the base for the most common category of Harappan ceramics, known as Red Ware.
- Varieties:
- Plain Pottery: This is more abundant than painted ware and consists of simple red clay vessels.
- Painted Pottery: Often referred to as Black-on-Red Ware, this variety uses the same red clay base (often with a red slip) featuring geometric and animal designs painted in black.
Key Takeaway: The quintessential Harappan pottery is wheel-made Red Ware, derived from red clay that turns reddish-brown upon firing, serving as the canvas for the famous Black-on-Red painted designs.