Dark bands are

Options

A. A-band
B. B-band
C. I-band
D. Ziline.

Explanation

**Step-by-Step Solution:**

1. **Understanding Muscle Structure**: Skeletal muscles are voluntary muscles that are striated in appearance. They consist of muscle fibers that exhibit alternating light and dark bands when viewed under a microscope.

2. **Identifying the Components**: The two main contractile proteins in skeletal muscles are actin and myosin. Actin is known as the thin filament, while myosin is referred to as the thick filament.

3. **Recognizing the Bands**: The light bands in skeletal muscles are called I bands (isotropic bands), which are primarily composed of actin. The dark bands are known as A bands (anisotropic bands), which are predominantly made up of myosin.

4. **Analyzing the Appearance**: The striated appearance of skeletal muscles is due to the arrangement of these proteins. The actin filaments (light) and myosin filaments (dark) overlap, creating the characteristic banding pattern.

5. **Conclusion**: Since the dark bands are associated with myosin, the correct answer to the question "Dark bands are?" is the A band.

**Final Answer**: Dark bands are the A band, which is made up of myosin protein.

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