Ketones do not reduce Tollen's reagents, but fructose with a keto group reduces it. It is attributed to.

Options

A. Enolisation of keto group of fructose and then, its transformation into aldehyde group in presence of `OH^(-)` which is present in Tollen's reagent.
B. `gt CHOH` group which is also oxidised to keto group
C. Both statements are correct
D. None of the statement is correct

Explanation

### Step-by-Step Solution:

1. **Understanding the Components**:
- Fructose is a monosaccharide with a keto group (ketone).
- Tollen's reagent is a chemical test used to identify aldehydes, as they can reduce the reagent.

2. **Key Concept - Enolization**:
- In an alkaline medium, fructose can undergo a process called enolization. This is where the keto group (C=O) transforms into an enol form (C=C-OH).
- The enol form is formed by the migration of a hydrogen atom and the shifting of the double bond.

3. **Formation of Aldehyde**:
- When fructose enolizes, the keto group can rearrange to form an aldehyde group. This occurs when the double bond shifts, resulting in a free aldehyde functional group.
- The reaction can be illustrated as follows:
- The keto form (C=O) of fructose converts to an enol form (C=C-OH).
- The enol can then rearrange to produce an aldehyde (R-CHO).

4. **Equilibrium with Other Sugars**:
- Fructose is in equilibrium with glucose and mannose, both of which also have free aldehyde groups.
- This means that even though fructose itself has a keto group, it can still participate in reactions that involve aldehydes due to this equilibrium.

5. **Conclusion**:
- The ability of fructose to reduce Tollen's reagent is attributed to its enolization in an alkaline medium, which allows it to form an aldehyde group. This is why fructose can reduce Tollen's reagent, unlike other ketones that do not have this capability.