## **Core Concept**
The respiratory quotient (RQ) is a measure used in physiology to describe the ratio of carbon dioxide (CO2) produced to oxygen (O2) consumed during the process of cellular respiration. It varies depending on the type of nutrient being metabolized. For carbohydrates, the general equation for cellular respiration can be simplified.

## **Why the Correct Answer is Right**
The metabolism of carbohydrates can be represented by the equation: C6H12O6 + 6O2 → 6CO2 + 6H2O. From this equation, it is clear that 6 molecules of CO2 are produced for every 6 molecules of O2 consumed. Therefore, the respiratory quotient (RQ) for carbohydrates, which is the ratio of CO2 produced to O2 consumed, is 1. This makes option **B. 1** the correct answer.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option suggests an RQ of less than 1, which could be true for fats but not for carbohydrates.
- **Option C:** and **Option D:** suggest RQ values greater than 1 or not equal to 1, which do not accurately represent the RQ for carbohydrate metabolism.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that the RQ can vary depending on the substrate being metabolized: it is approximately 1 for carbohydrates, 0.8 for proteins, and 0.7 for fats. This knowledge can be crucial in critical care settings for assessing a patient's metabolic state.

## **Correct Answer: B. 1**