The intermediates involved in the given transformation are

Concept:

The reaction involves 3 steps-

1. Acid-base reaction
2. Substitution reaction
3. E₁CB elimination reaction

Where OH^- acts as a base and reacts with acidic H⁺ of 1-(chloromethyl)-4-nitrobenzene to give final product via intermediates.

Explanation:

The mechanism of the reaction is given below

• Acid base reaction 

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• SN² Substitution reaction 

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• E₁CB elimination reaction 

Conclusion:

Hence, the intermediates involved in the reaction are A and B.