A ketose sugar is

Options

A. Glucose
B. Fructose
C. Glyceraldehyde
D. Both A and B.

Answer

To determine which of the given options is a ketose sugar, we need to understand the definition and characteristics of ketose sugars.

### Step-by-Step Solution:

1. **Understand the Definition of Ketose Sugar**:
- A ketose sugar is a type of monosaccharide (simple sugar) that contains one ketone group in its molecular structure.

2. **Identify the Options**:
- The options provided are:
- A) Glucose
- B) Fructose
- C) Glyceraldehyde
- D) Both A and B

3. **Analyze Each Option**:
- **Option A: Glucose**:
- Glucose is an aldohexose, meaning it has an aldehyde group, not a ketone group. Therefore, glucose is not a ketose sugar.
- **Option B: Fructose**:
- Fructose is a ketose sugar because it contains a ketone group in its structure. This makes fructose a correct option.
- **Option C: Glyceraldehyde**:
- Glyceraldehyde is a triose and is classified as an aldose because it has an aldehyde group. Thus, it is not a ketose sugar.
- **Option D: Both A and B**:
- Since option A (glucose) is not a ketose sugar, this option is also incorrect.

4. **Conclusion**:
- The only correct answer is **B) Fructose**, as it is the only option that qualifies as a ketose sugar.

### Final Answer:
**B) Fructose**