Which of the following components is required only for respiration?

Options

A. Energy
B. Chlorophyll
C. Carbon dioxide
D. Oxygen

Answer

### Step-by-Step Solution:

1. **Understanding Cellular Respiration**:
- Cellular respiration is a process where glucose (a carbohydrate) is broken down to produce energy.
- This process occurs in the presence of oxygen and involves enzymes.

2. **Identifying the Components**:
- The options given are energy, chlorophyll, carbon dioxide, and oxygen.
- We need to determine which of these components is specifically required only for respiration.

3. **Analyzing Each Option**:
- **Energy**: While energy is produced during respiration, it is not a component that is required to initiate the process.
- **Chlorophyll**: This is essential for photosynthesis, not respiration.
- **Carbon Dioxide**: This gas is a by-product of respiration and is also required for photosynthesis.
- **Oxygen**: This is crucial for cellular respiration as it is needed for the breakdown of glucose to release energy.

4. **Conclusion**:
- Among the options, oxygen is the only component that is specifically required for the process of respiration.
- Therefore, the answer is **Oxygen** (Option D).