Which one of the following statements regarding CO gas is correct ?

Options

A. It is produced by the complete combustion of fossil fuels.
B. It combines with haemoglobin to form carbamino-haemoglobin.
C. It impairs oxygen transport resulting in giddiness, headache, asphyxia and even death.
D. All of these

Explanation

To determine the correct statement regarding carbon monoxide (CO) gas, we will analyze each option provided in the question step by step.

### Step 1: Analyze the first statement
The first statement claims that CO is produced by the complete combustion of fossil fuels.
- **Evaluation**: This statement is incorrect. Carbon monoxide is actually produced by the incomplete combustion of fossil fuels. When there is insufficient oxygen for complete combustion, CO is formed as a byproduct.

### Step 2: Analyze the second statement
The second statement suggests that CO combines with hemoglobin to form carbaminohemoglobin.
- **Evaluation**: This statement is also incorrect. When carbon monoxide combines with hemoglobin, it forms carboxyhemoglobin, not carbaminohemoglobin. Carbaminohemoglobin is formed when carbon dioxide binds with hemoglobin.

### Step 3: Analyze the third statement
The third statement states that CO impairs oxygen transport, resulting in symptoms such as giddiness, headache, asphyxia, and even death.
- **Evaluation**: This statement is correct. Carbon monoxide has a high affinity for hemoglobin, which means it binds strongly to it. This binding reduces the ability of hemoglobin to carry oxygen, leading to impaired oxygen transport in the body. The symptoms mentioned are indeed associated with carbon monoxide poisoning.

### Conclusion
Based on the evaluations:
- The first statement is incorrect.
- The second statement is incorrect.
- The third statement is correct.

Thus, the correct answer is **option 3**.