The metals that produce ringing sounds, are said to be:

Options

A. malleable
B. sonorous
C. lustrous
D. hard

Explanation

To answer the question, "The metals that produce ringing sounds are said to be:", we will analyze the properties of metals and identify the correct term that describes metals producing ringing sounds.

### Step-by-Step Solution:

1. **Understanding the Question**: The question is asking for the specific term used to describe metals that produce a ringing sound when struck.

2. **Identifying Properties of Metals**:
- **Malleable**: This property refers to metals that can be beaten into thin sheets. For example, aluminum can be made into foil. However, malleability does not relate to producing sound, so this option is incorrect.

3. **Exploring the Term "Sonorous"**:
- **Sonorous**: This term specifically refers to metals that produce a ringing sound when they are struck. When a sonorous metal is hit, it resonates and creates a sound. Therefore, this property directly answers the question.

4. **Examining Other Properties**:
- **Lustrous**: This property describes metals that have a shiny surface. While lustrous metals are visually appealing, they do not inherently produce sound, making this option incorrect.
- **Hard**: Metals are generally hard due to strong intermolecular forces, but hardness does not correlate with the ability to produce sound. Thus, this option is also incorrect.

5. **Conclusion**: Based on the analysis of the properties, the correct answer to the question is that metals which produce ringing sounds are said to be **sonorous**.

### Final Answer:
The metals that produce ringing sounds are said to be **sonorous**.