Among the naturally occuring carbohydrates, furanose ring is found in the

Options

A. glucose unit of cane sugar
B. glucose unit of cellulose
C. fructose unit of cane sugar
D. galactose unit of lactose.

Explanation

To determine which naturally occurring carbohydrate contains a furanose ring, we can follow these steps:

### Step 1: Understand the Structure of Carbohydrates
Carbohydrates can exist in cyclic forms, which are classified based on the number of atoms in the ring. The two common types of cyclic forms are pyranose and furanose.

### Step 2: Identify Pyranose and Furanose
- **Pyranose**: This is a six-membered ring structure that includes five carbon atoms and one oxygen atom. It is commonly found in sugars like glucose and galactose.
- **Furanose**: This is a five-membered ring structure that includes four carbon atoms and one oxygen atom.

### Step 3: Identify the Carbohydrates
Among the common carbohydrates:
- **Glucose**: Contains a pyranose ring.
- **Galactose**: Also contains a pyranose ring.
- **Fructose**: Contains a furanose ring.

### Step 4: Conclusion
Since fructose is the carbohydrate that contains a furanose ring, the correct answer to the question is that furanose rings are found in fructose.

### Final Answer
The naturally occurring carbohydrate that contains a furanose ring is **fructose**.

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