Consider for following four statements and select the correct option starting which ones are true `(T)` and which ones are flase (F).
(i) Expiration is normally brough about by the relaxation of inspiratory muscles.
(ii) Oxyhaemoglobin can hold much less carbon dioxide in the form of carbaminohaemoglobin than what deoxyhaemoglobin can.
(iii) A person can expel all the air from the lungs by a forceful expiration.
(iv) A rise in `PCO_(2)` increases the oxygen-affinity of haemoglobin.

Options

A. `{:("(i)",(ii),(iii),(iv)),(F,F,T,F):}`
B. `{:("(i)"1,(ii),(iii),(iv)),(T,T,F,F):}`
C. `{:("(i)",(ii),(iii),(iv)),(F,T,T,F):}`
D. `{:("(i)",(ii),(iii),(iv)),(T,T,T,F):}`

Explanation

To determine the truth value of each statement, let's analyze them one by one:

### Step-by-Step Solution:

1. **Statement (i): Expiration is normally brought about by the relaxation of inspiratory muscles.**
- **Analysis:** Expiration is indeed a passive process that occurs when the inspiratory muscles (like the diaphragm and intercostal muscles) relax after inhalation. This allows the lungs to recoil and expel air.
- **Conclusion:** This statement is **True (T)**.

2. **Statement (ii): Oxyhaemoglobin can hold much less carbon dioxide in the form of carbaminohaemoglobin than what deoxyhaemoglobin can.**
- **Analysis:** Oxyhaemoglobin (hemoglobin bound to oxygen) has a lower capacity to bind carbon dioxide compared to deoxyhaemoglobin (hemoglobin that is not bound to oxygen). This is due to the fact that when oxygen is bound to hemoglobin, it changes the structure of hemoglobin, making it less able to bind carbon dioxide.
- **Conclusion:** This statement is **True (T)**.

3. **Statement (iii): A person can expel all the air from the lungs by a forceful expiration.**
- **Analysis:** It is not possible for a person to expel all the air from the lungs, even during a forceful expiration. There is always some residual volume of air that remains in the lungs (approximately 1100-1200 ml) to prevent lung collapse.
- **Conclusion:** This statement is **False (F)**.

4. **Statement (iv): A rise in PCO2 increases the oxygen-affinity of haemoglobin.**
- **Analysis:** An increase in the partial pressure of carbon dioxide (PCO2) actually decreases the affinity of hemoglobin for oxygen, which is known as the Bohr effect. This means that as CO2 levels rise, hemoglobin is more likely to release oxygen.
- **Conclusion:** This statement is **False (F)**.

### Final Summary of Truth Values:
- (i) True (T)
- (ii) True (T)
- (iii) False (F)
- (iv) False (F)

### Correct Option:
The correct option is that the first two statements are true and the last two statements are false.

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