The correct sequence of events during relaxation of muscle is `:-`
(i) Inactivation of the actin
(ii) `Ca^(++)` returend to SR
(iii) Cross bridges are boken

Options

A. (i),(ii),(iii)
B. (ii),(i),(iii)
C. (ii),(iii),(i)
D. (iii),(ii),(i)

Answer

To determine the correct sequence of events during the relaxation of a muscle, we need to analyze the process step by step.

### Step-by-Step Solution:

1. **Calcium Ions Return to Sarcoplasmic Reticulum (SR)**:
- When muscle contraction occurs, calcium ions are released from the sarcoplasmic reticulum into the cytoplasm, facilitating the interaction between actin and myosin. During relaxation, these calcium ions are pumped back into the sarcoplasmic reticulum, leading to a decrease in calcium concentration in the cytoplasm.

2. **Inactivation of Actin**:
- As the concentration of calcium ions decreases, the binding sites on actin for myosin are blocked by tropomyosin. This process effectively inactivates actin, preventing further cross-bridge formation between actin and myosin.

3. **Cross Bridges are Broken**:
- With actin inactivated and calcium levels low, the existing cross-bridges between actin and myosin are broken. This leads to muscle relaxation as the myosin heads detach from the actin filaments.

### Correct Sequence:
Based on the above steps, the correct sequence of events during muscle relaxation is:
1. Calcium returned to SR (ii)
2. Inactivation of the actin (i)
3. Cross bridges are broken (iii)

Thus, the correct order is:
(ii) → (i) → (iii)

### Final Answer:
The correct sequence of events during relaxation of muscle is:
1. Calcium returned to SR
2. Inactivation of the actin
3. Cross bridges are broken