Which of the following materials is not lustrous?

Options

A. Gold
B. Silver
C. Wood
D. Diamond

Explanation

### Step-by-Step Solution:

1. **Understanding Lustrous Materials**: Lustrous materials are those that have a shiny appearance, similar to metals. They reflect light well and are often used in jewelry. Common examples of lustrous materials include gold, silver, and diamonds.

2. **Identifying the Options**: The question asks which of the following materials is not lustrous. The materials provided are:
- Option 1: Gold
- Option 2: Silver
- Option 3: Wood
- Option 4: Diamond

3. **Analyzing Each Option**:
- **Gold**: This is a lustrous material, known for its shiny appearance.
- **Silver**: This is also a lustrous material, widely used in jewelry.
- **Wood**: This is not lustrous; it has a dull appearance and does not reflect light like metals.
- **Diamond**: Diamonds are known for their brilliance and are considered lustrous.

4. **Conclusion**: Since gold, silver, and diamond are all lustrous materials, the only material that is not lustrous is wood.

5. **Final Answer**: Therefore, the correct answer is **Option 3: Wood**.