Read the given Statements for skeletal muscles
(i) Thin filaments are firmly attached to the Z - line .
(ii) The light band is also called the I - band and contains mostly actin.
(iii) A sarcomere is the functional unit of a myofibril between two adjacent A - bands .
(iv) The central part of the thick filament , not overlapped by the thick filament is called the H - zone
Which of these is/are CORRECT ?

Options

A. i, ii, iii, iv
B. i, ii, iii
C. i, ii, iv
D. i, ii

Answer

To determine which statements about skeletal muscles are correct, let's analyze each statement step by step.

### Step-by-Step Solution:

1. **Statement (i): Thin filaments are firmly attached to the Z-line.**
- This statement is **correct**. In skeletal muscle fibers, thin filaments (primarily composed of actin) are indeed anchored to the Z-line, which defines the boundaries of a sarcomere.

2. **Statement (ii): The light band is also called the I-band and contains mostly actin.**
- This statement is also **correct**. The I-band is the light band in a sarcomere and is primarily made up of thin filaments (actin).

3. **Statement (iii): A sarcomere is the functional unit of a myofibril between two adjacent A-bands.**
- This statement is **incorrect**. A sarcomere is defined as the segment between two adjacent Z-lines, not between A-bands. The A-band represents the dark band where thick filaments (myosin) are present, but the functional unit is bounded by Z-lines.

4. **Statement (iv): The central part of the thick filament, not overlapped by the thin filament, is called the H-zone.**
- This statement is **correct**. The H-zone is indeed the area within the A-band where there is no overlap with thin filaments, representing the central part of the thick filaments.

### Conclusion:
Based on the analysis:
- **Correct Statements:** (i), (ii), and (iv)
- **Incorrect Statement:** (iii)

Thus, the correct answer is that statements **1, 2, and 4 are correct**.