Which is incorrect about muscle contraction:-

Options

A. Length of A-band remain same
B. Length of thin filament is reduced
C. Length of sarcomere is reduced
D. Length of I-band is reduced

Answer

To determine which statement about muscle contraction is incorrect, we need to analyze the process of muscle contraction and the roles of different components involved.

### Step-by-Step Solution:

1. **Understanding Muscle Contraction**:
- Muscle contraction occurs in the sarcomere, which is the structural and functional unit of muscle fibers.

2. **Components of Sarcomere**:
- The sarcomere consists of thick filaments (myosin) and thin filaments (actin).

3. **Behavior of Filaments During Contraction**:
- During contraction, the thick and thin filaments do not shorten. Instead, they slide past each other. This sliding mechanism is known as the sliding filament theory.

4. **Effect on Sarcomere Length**:
- As the thick and thin filaments slide over one another, the overall length of the sarcomere decreases. Thus, the sarcomere shortens during contraction.

5. **Length of A Band and I Band**:
- The A band (which contains the thick filaments) remains the same length during contraction because the thick filaments do not change in length.
- The I band (which contains only thin filaments) decreases in length as the sarcomere shortens.

6. **Identifying the Incorrect Statement**:
- Based on the above points, if a statement claims that the length of thin filaments is reduced, this is incorrect because the length of the filaments themselves does not change during contraction. Only the sarcomere shortens.

### Conclusion:
The incorrect statement about muscle contraction is that the length of thin filaments is reduced.

---