Respiratory quotient (R.Q) is one in case of :

Options

A. Fatty acids
B. Nucleic acids
C. Carbohydrates
D. Organic acids

Explanation

To determine the correct answer to the question about the respiratory quotient (R.Q), we will analyze the R.Q values for different types of substrates.

### Step-by-Step Solution:

1. **Understanding Respiratory Quotient (R.Q)**:
- The respiratory quotient (R.Q) is defined as the ratio of the volume of carbon dioxide (CO2) produced to the volume of oxygen (O2) consumed during respiration over a specific period.
- Mathematically, it can be expressed as:
\[ R.Q = \frac{CO2 \text{ produced}}{O2 \text{ consumed}} \]

2. **Analyzing Different Substrates**:
- **Fatty Acids**:
- The R.Q for fatty acids is approximately 0.7. This means that for every molecule of oxygen consumed, less carbon dioxide is produced, indicating that fatty acids yield less CO2 relative to O2 during respiration.
- **Conclusion**: R.Q = 0.7 (not the answer).

- **Nucleic Acids**:
- The R.Q for nucleic acids is not commonly specified, but it is generally considered to be less than 1, similar to proteins.
- **Conclusion**: R.Q < 1 (not the answer).

- **Carbohydrates**:
- The R.Q for carbohydrates is exactly 1. This is because during the complete oxidation of glucose (a common carbohydrate), the amount of CO2 produced is equal to the amount of O2 consumed.
- **Conclusion**: R.Q = 1 (this is the correct answer).

- **Organic Acids**:
- The R.Q for organic acids is approximately 1.33. This indicates that more CO2 is produced than O2 consumed during their respiration.
- **Conclusion**: R.Q = 1.33 (not the answer).

3. **Final Answer**:
- After analyzing all the options, the only substrate with an R.Q of 1 is carbohydrates.

### Answer: Carbohydrates (Option 3)

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