What is true for respiration

Options

A. Oxygen is essential
B. Oxygen combines with carbon form `CO_(2)`
C. Oxygen combines with hydrogen to produce water
D. Oxygen is not essential

Answer

### Step-by-Step Solution:

1. **Understanding Respiration**:
- Respiration is a metabolic process where glucose is broken down to release energy in the form of ATP. This energy is crucial for various bodily functions.

2. **Analyzing the Options**:
- **Option 1**: "Oxygen is essential."
- This statement is partially correct. While aerobic respiration requires oxygen, anaerobic respiration occurs without it. Thus, this option is not entirely true.

- **Option 2**: "Oxygen combines with carbon to form carbon dioxide."
- This statement is incorrect. The process of respiration does not involve oxygen directly combining with carbon to form carbon dioxide in this manner.

- **Option 3**: "Oxygen combines with hydrogen to produce water."
- This statement is correct. In cellular respiration, oxygen does combine with hydrogen (from glucose) to form water as a byproduct.

- **Option 4**: "Oxygen is not essential."
- This statement is also partially correct. While anaerobic respiration does not require oxygen, aerobic respiration does. Therefore, this option is misleading.

3. **Conclusion**:
- After evaluating all the options, the correct statement regarding respiration is **Option 3**: "Oxygen combines with hydrogen to produce water."