Monosaccharide is

Options

A. pentose sugar
B. Hexose sugar
C. only Glucose
D. All the above

Answer

To answer the question "Monosaccharide is," we need to analyze the definition and characteristics of monosaccharides and the options provided.

### Step-by-Step Solution:

1. **Understanding Monosaccharides**:
- Monosaccharides are the simplest form of carbohydrates. They are single sugar units.
- The term "mono" means one, and "saccharide" means sugar. Therefore, monosaccharides are single sugar molecules.

2. **Examples of Monosaccharides**:
- Common examples of monosaccharides include glucose and fructose.
- Glucose is classified as a hexose sugar because it contains six carbon atoms and has a hexagonal ring structure.
- Fructose, on the other hand, is classified as a pentose sugar because it has five carbon atoms and a pentagonal ring structure.

3. **Analyzing the Options**:
- **Option A: Pentose sugar** - This is correct because fructose is a pentose sugar.
- **Option B: Hexose sugar** - This is also correct because glucose is a hexose sugar.
- **Option C: Only glucose** - This is partially correct because glucose is a monosaccharide, but it does not encompass all monosaccharides.
- **Option D: All the above** - This option includes all previous options, which are correct.

4. **Conclusion**:
- Since options A and B are correct, and option C is partially correct, the best choice that encompasses all possibilities is option D: "All the above."

### Final Answer:
The correct answer is **All the above**.

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