`1^@` allylic halides are more reactive than `1^@ RX` in `SN^1` reaction.
Allylic carbocation intermediate is stabilished by resonance.

Options

A. If both `(A)` and `(R )` are true, but `( R)` is the correct explanation of `(A)`
B. If both `(A)` and `( R)` are true, but `(R )` is not the correct explanation of `(A)`.
C. If `(A)` is true but `( R)` is false.
D. If `(A)` is false but `( R)` is true.

Explanation

To solve the question regarding the reactivity of 1° allylic halides compared to 1° alkyl halides in SN1 reactions, we will break down the reasoning step by step.

### Step-by-Step Solution:

1. **Understanding Allylic Halides and Alkyl Halides**:
- Allylic halides are compounds where the halogen is attached to a carbon atom adjacent to a double bond (e.g., CH2=CH-CH2X).
- Alkyl halides have the halogen attached to a saturated carbon atom (e.g., CH3X).

2. **SN1 Reaction Mechanism**:
- The SN1 (Substitution Nucleophilic Unimolecular) reaction involves two main steps:
1. Formation of a carbocation intermediate after the leaving group departs.
2. Nucleophilic attack on the carbocation.

3. **Stability of Carbocations**:
- The stability of the carbocation formed in the first step is crucial for the reactivity of the halide.
- 1° carbocations (like those formed from 1° alkyl halides) are generally less stable than 2° or 3° carbocations.

4. **Resonance Stabilization in Allylic Carbocations**:
- Allylic carbocations can be stabilized through resonance. For example, when the leaving group departs from an allylic halide, the positive charge can be delocalized over the adjacent double bond.
- This resonance stabilization significantly increases the stability of the allylic carbocation compared to a simple 1° alkyl carbocation.

5. **Comparative Reactivity**:
- Due to the resonance stabilization, 1° allylic halides are more reactive in SN1 reactions than 1° alkyl halides.
- In contrast, 1° alkyl halides do not benefit from such stabilization and are less reactive in SN1 reactions.

6. **Conclusion**:
- Both statements in the question are true: 1° allylic halides are indeed more reactive than 1° alkyl halides in SN1 reactions, and this is due to the resonance stabilization of the allylic carbocation intermediate.

### Final Answer:
Both assertion and reason are true, and the reason is a correct explanation of the assertion.

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