**Core Concept**
Respiratory quotient (RQ) is a measure of the ratio of carbon dioxide production to oxygen consumption during respiration. It is an indicator of the type of fuel being metabolized by the body, with a value of 1 indicating complete oxidation of carbohydrates, 0.7 indicating complete oxidation of fats, and 0.9 indicating a mixed diet.

**Why the Correct Answer is Right**
When a person consumes a heavy carbohydrate meal, the body's primary source of energy is glucose. The complete oxidation of glucose (C6H12O6) to carbon dioxide and water releases 6 molecules of carbon dioxide and 6 molecules of water per molecule of glucose. This results in a respiratory quotient of 1, as the number of carbon dioxide molecules produced is equal to the number of oxygen molecules consumed. The increased RQ value reflects the body's increased reliance on carbohydrate metabolism.

**Why Each Wrong Option is Incorrect**
**Option A:** This option would be incorrect as it suggests a value less than 0.7, indicating fat metabolism, which is not relevant to carbohydrate consumption.

**Option B:** This option would be incorrect as it suggests a value of 0.9, indicating a mixed diet, which is not specific to carbohydrate metabolism.

**Option D:** This option would be incorrect as it suggests a value greater than 1, which is not physiologically possible for carbohydrate metabolism.

**Clinical Pearl / High-Yield Fact**
Remember that an RQ value of 1 indicates complete oxidation of carbohydrates, whereas an RQ value of 0.7 indicates complete oxidation of fats.

**Correct Answer:** C. 1