The question image/reaction scheme and the actual option structures are missing. The prompt only says:

In the following reaction, 'A' is

but no reaction, no reactants/reagents, and no option identities for A/B/C/D are provided.

Because of this, the compound $A$ cannot be determined from the given text alone.

What is needed

To solve the problem, I need either:

1. the reaction scheme/image, or
2. the reactant, reagents, and products written in text, and
3. the actual structures corresponding to options A, B, C, and D.

Conclusion

With the current information, the answer cannot be derived logically. Therefore I cannot verify whether option $B$ is truly correct from chemistry reasoning alone.