A monosaccharide is

Options

A. Lactose
B. Sucrose
C. Ribose
D. Maltose

Answer

To determine which of the given options is a monosaccharide, we can analyze each option based on their definitions and compositions.

### Step-by-Step Solution:

1. **Understanding Monosaccharides**:
- Monosaccharides are the simplest form of carbohydrates and cannot be hydrolyzed into simpler sugars. They typically consist of a single sugar unit.

2. **Analyzing the Options**:
- **A. Lactose**:
- Lactose is a disaccharide composed of two monosaccharides: glucose and galactose. Therefore, it is not a monosaccharide.
- **B. Sucrose**:
- Sucrose is also a disaccharide made up of glucose and fructose. Since it can be broken down into two monosaccharides, it is not a monosaccharide.
- **C. Ribose**:
- Ribose is a monosaccharide, specifically a pentose sugar, which means it cannot be further hydrolyzed into simpler sugars. Thus, it qualifies as a monosaccharide.
- **D. Maltose**:
- Maltose is another disaccharide that consists of two glucose units. It can be broken down into two monosaccharides, making it not a monosaccharide.

3. **Conclusion**:
- Among the options provided, only Ribose (option C) is a monosaccharide. Therefore, the correct answer is **C. Ribose**.

### Final Answer:
The correct answer is **C. Ribose**.

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