Crystalline polymers are

Options

A. Harder
B. Denser
C. Heavier
D. None of these

Explanation

### Step-by-Step Solution:

1. **Definition of Crystalline Polymers**:
- Crystalline polymers are materials that have a highly ordered structure. The polymer chains are arranged in a regular, repeating pattern, which gives them unique properties.

2. **Properties of Crystalline Polymers**:
- **Hardness**: Crystalline polymers tend to be harder than their amorphous counterparts due to their tightly packed molecular structure.
- **Density**: They are usually denser because of the close packing of the polymer chains.
- **Thermal Conductivity**: Crystalline polymers generally do not conduct heat well. This is because the orderly structure does not allow for free movement of heat through the material.

3. **Comparison with Amorphous Polymers**:
- Unlike crystalline polymers, amorphous polymers have a random arrangement of chains, which can lead to different properties such as lower density and different thermal and mechanical behaviors.

4. **Conclusion**:
- Based on the properties discussed, crystalline polymers are characterized as being hard, dense, and poor conductors of heat.