Read the following statements carefully
(i) In fishes, the heart pumps out deoxygenated blood which is oxygenated by the gills and supplied to the body parts from where deoxygenated blood is returned to the heart.
(ii) The openings of the right and the left ventricle into pulmonary artery and aorta respectively are provided with the mitral valves.
(iii) The nodal musculature has the ability to generate action potential without any external stimuli, i,e., it is autoexcitable.
(iv) The T-wave of ECG represents depolarisation of the ventricles.
Which of the above four statements are incorrect?

Options

A. (a) (i) and (ii)
B. (b) (ii) and (iv)
C. (c) (i) and (ii)
D. (d) (iii) and (iv)

Explanation

To determine which of the four statements are incorrect, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement (i)**: "In fishes, the heart pumps out deoxygenated blood which is oxygenated by the gills and supplied to the body parts from where deoxygenated blood is returned to the heart."
- **Analysis**: This statement is correct. In fish, the heart is two-chambered and pumps deoxygenated blood to the gills, where it is oxygenated before being distributed to the body.

2. **Statement (ii)**: "The openings of the right and the left ventricle into pulmonary artery and aorta respectively are provided with the mitral valves."
- **Analysis**: This statement is incorrect. The openings from the right ventricle to the pulmonary artery and the left ventricle to the aorta are equipped with semilunar valves, not mitral valves. The mitral valve is located between the left atrium and left ventricle.

3. **Statement (iii)**: "The nodal musculature has the ability to generate action potential without any external stimuli, i.e., it is autoexcitable."
- **Analysis**: This statement is correct. The sinoatrial (SA) node, which is part of the nodal musculature, can generate action potentials independently, making it autoexcitable.

4. **Statement (iv)**: "The T-wave of ECG represents depolarisation of the ventricles."
- **Analysis**: This statement is incorrect. The T-wave in an electrocardiogram (ECG) represents the repolarization of the ventricles, not depolarization.

### Conclusion:
The incorrect statements are:
- Statement (ii): Incorrect (it mentions mitral valves instead of semilunar valves).
- Statement (iv): Incorrect (it states T-wave represents depolarization instead of repolarization).

### Final Answer:
The incorrect statements are **(ii) and (iv)**.

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