Consider the following four statements (i)-(iv) and select the correct option
(i) Fish heart contains only oxygenated blood
(ii) Closure of A-V valves produces the second heart sound
(iii) The vascular connection between the digestive track and kidney is called hepatic portal system
(iv) Purkinje fibres are nerve fibres present in the heart wall.

Options

A. `{:("(i) (ii) (iii) (iv)"),("F F T F"):}`
B. `{:("(i) (ii) (iii) (iv)"),("F F F T"):}`
C. `{:("(i) (ii) (iii) (iv)"),("T T F T"):}`
D. `{:("(i) (ii) (iii) (iv)"),("T F T F"):}`

Explanation

To solve the question, we need to evaluate each of the four statements provided and determine which ones are correct.

### Step-by-Step Solution:

1. **Evaluate Statement (i)**: "Fish heart contains only oxygenated blood."
- Fish have a two-chambered heart consisting of one atrium and one ventricle. The heart pumps deoxygenated blood to the gills, where it gets oxygenated. Therefore, the statement is **false** because the fish heart contains both oxygenated and deoxygenated blood.

2. **Evaluate Statement (ii)**: "Closure of A-V valves produces the second heart sound."
- The first heart sound (S1) is produced by the closure of the atrioventricular (A-V) valves (mitral and tricuspid valves). The second heart sound (S2) is produced by the closure of the semilunar valves (aortic and pulmonary). Therefore, this statement is also **false**.

3. **Evaluate Statement (iii)**: "The vascular connection between the digestive tract and kidney is called hepatic portal system."
- The hepatic portal system refers to the vascular connection between the digestive tract and the liver, not the kidney. Therefore, this statement is **false**.

4. **Evaluate Statement (iv)**: "Purkinje fibres are nerve fibres present in the heart wall."
- Purkinje fibers are specialized muscle fibers that conduct electrical impulses in the heart, not nerve fibers. However, they play a crucial role in the heart's conduction system. The statement is **true**.

### Conclusion:
Based on the evaluations:
- Statement (i): False
- Statement (ii): False
- Statement (iii): False
- Statement (iv): True

Thus, the correct option is that only statement (iv) is true.

### Final Answer:
The correct option is that only statement (iv) is true.

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