I band has

Options

A. only actin filaments
B. only myosin filaments
C. both actin and myosin filaments
D. one sarcomere

Answer

### Step-by-Step Solution

1. **Understanding the I-band**: The I-band is a specific region found in striated muscle tissue. It is important to know that the I-band is part of the sarcomere, which is the basic contractile unit of muscle fibers.

2. **Composition of the I-band**: The I-band is characterized by the presence of thin filaments. Specifically, it contains only actin filaments. Actin is a protein that plays a crucial role in muscle contraction.

3. **Distinguishing the A-band**: In contrast to the I-band, the A-band contains thick filaments, primarily made up of myosin. The A-band is where the thick and thin filaments overlap, which is essential for muscle contraction.

4. **Conclusion**: Since the I-band contains only actin filaments and no myosin filaments, the correct answer to the question "I band has" is that it has only actin filaments.

5. **Final Answer**: The I-band has only actin filaments.