Pentoses and hexoses are the most common
Or
The simple polyhydroxy ketone molecule containing 3-7 carbons is a

Options

A. Oligosaccharides
B. Disachharides
C. Monosaccharides
D. Polysachharides

Answer

To solve the question regarding pentoses and hexoses, and to identify the simple polyhydroxy ketone molecule containing 3-7 carbons, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Carbohydrates**:
- Carbohydrates are biomolecules made up of carbon, hydrogen, and oxygen. They can be classified based on the number of sugar units they contain.

2. **Classification of Carbohydrates**:
- **Monosaccharides**: These are the simplest form of carbohydrates, consisting of a single sugar unit. They can have 3 to 7 carbon atoms.
- **Disaccharides**: These consist of two monosaccharide units.
- **Oligosaccharides**: These contain 2 to 20 monosaccharide units.
- **Polysaccharides**: These are complex carbohydrates made of more than 20 monosaccharide units.

3. **Identifying Pentoses and Hexoses**:
- Pentoses are monosaccharides with 5 carbon atoms (e.g., ribose).
- Hexoses are monosaccharides with 6 carbon atoms (e.g., glucose).
- Both pentoses and hexoses fall under the category of monosaccharides.

4. **Understanding the Question**:
- The question states that pentoses and hexoses are the most common, which aligns with the definition of monosaccharides.
- It also mentions "simple polyhydroxy ketone molecules containing 3-7 carbon atoms," which refers to monosaccharides as they can have 3 to 7 carbon atoms and can be either aldoses or ketoses.

5. **Conclusion**:
- Since both statements in the question refer to monosaccharides, the correct answer is **monosaccharides**.

### Final Answer:
The correct option is **monosaccharides**.

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