Intercalated disc and cross connections are the characteristic features of

Options

A. Cardiac muscles
B. Skeletal muscles
C. Smooth muscles
D. voluntary muscle

Answer

### Step-by-Step Solution:

1. **Understanding the Terms**:
- Intercalated discs are specialized structures found in certain types of muscle tissue. They play a crucial role in the function of these muscles.

2. **Identifying Muscle Types**:
- There are three main types of muscle tissue: cardiac muscle, smooth muscle, and skeletal muscle. Each has distinct characteristics.

3. **Analyzing Cardiac Muscle**:
- Cardiac muscle is unique because it has intercalated discs. These discs are junctions that connect individual cardiac muscle cells (myocytes) and allow them to function as a synchronized unit.

4. **Function of Intercalated Discs**:
- The intercalated discs contain gap junctions and desmosomes. Gap junctions facilitate electrical communication between cells, allowing them to contract simultaneously. Desmosomes provide structural support.

5. **Excluding Other Muscle Types**:
- Smooth muscle does not have intercalated discs; it operates involuntarily and does not require synchronized contractions.
- Skeletal muscle, while it can contract voluntarily, also lacks intercalated discs and has a different structure.

6. **Conclusion**:
- Based on the characteristics of intercalated discs and the types of muscle tissue, we conclude that intercalated discs are a characteristic feature of cardiac muscle.

### Final Answer:
Intercalated discs and cross connections are the characteristic features of **cardiac muscles**.

---