The question refers to a reaction sequence, but the actual reaction scheme/image is missing in the prompt. Also, the options are listed only as:

• A:
• B:
• C:
• D:

with no chemical structures or descriptions provided.

Because of this, it is not possible to determine the identities of compounds/reagents $A$, $B$, and $C$ from the given information.

What is missing?

To solve such a question, I would need:

1. The reaction sequence diagram showing the starting compound and products/intermediates.
2. The actual option contents (chemical structures/names under A, B, C, D).

Conclusion

With the current data, the problem is incomplete, so no chemistry-based derivation can be performed.

However, since you asked me to compare with the stored correct answer, the stored answer is B, but I cannot independently verify it from the information provided.