`SN^(2)` reaction is a bimolecular reaction which takes places by the formation of `T.S.` Veolcity of the reaction depends on the concentration of the substrate as well as the nucleophile.
The reaction is favoureed by strong `Nu^(o-)` and in the presence of polar aprotic sovlent, optically active halides give. Walken inversion by `SN^(2)` mechanism. The presence of hero group (atom) at `beta-C` atom, unsaturation at `beta-C` and `(-overset(O)overset(||)(C)-)` group at `alpha-C` atomn favor `SN^(2)` mechanism.
Allyl halides and benzyl halides give `SN^(1)` and `SN^(2)` reactions. Allyl halides alos give `SN^(2)` mechanism `EDG` at ortho- and para- postions in benzyl halides favors `SN^(1)` mechanism, wheras `EWG` favors `SN^(2)` mechanism.
Which of the following will give `SN^(1)` reaction?

Options

A.
B.
C.
D. All

Explanation

To determine which of the given compounds will undergo an SN1 reaction, we need to analyze the stability of the carbocations formed during the reaction. The SN1 mechanism involves the formation of a carbocation intermediate, and the stability of this carbocation is crucial for the reaction to proceed.

### Step-by-Step Solution:

1. **Understanding SN1 Mechanism**:
- The SN1 reaction is a two-step process where the first step involves the formation of a carbocation after the leaving group departs. The stability of this carbocation is key to whether the reaction will occur.

2. **Identifying the Compounds**:
- We need to evaluate the compounds provided in the question (let's call them A, B, and C) to see which ones can form stable carbocations.

3. **Analyzing Compound A**:
- Compound A is an allylic halide. When the leaving group (e.g., Cl) departs, it forms an allylic carbocation.
- Allylic carbocations are stabilized by resonance, which makes them relatively stable. Therefore, Compound A can undergo an SN1 reaction.

4. **Analyzing Compound B**:
- Compound B is a benzyl halide. When the leaving group leaves, it forms a benzyl carbocation.
- Benzyl carbocations are also resonance-stabilized due to the delocalization of charge over the aromatic ring. Thus, Compound B can also undergo an SN1 reaction.

5. **Analyzing Compound C**:
- Compound C also leads to the formation of a benzyl carbocation upon the departure of the leaving group.
- If there is an electron-donating group (like a methoxy group) at the para position, it will further stabilize the carbocation through resonance. Hence, Compound C can also undergo an SN1 reaction.

6. **Conclusion**:
- Since all three compounds (A, B, and C) can form stable carbocations, they are all capable of undergoing SN1 reactions. Therefore, the answer to the question is that all of the compounds will give an SN1 reaction.

### Final Answer:
All of the compounds (A, B, and C) will give an SN1 reaction.