The question asks for the major product of a reaction, but the actual reaction scheme/structure and the option structures A–D are missing in the prompt.

Because of that, the product cannot be determined from the provided information alone.

What is missing?

To solve this, I need:

1. The starting compound/reactant structure
2. The reagents/conditions
3. The structures corresponding to options A, B, C, and D

Without these, no chemical analysis can be performed reliably.

Comparison with stored answer

The stored correct answer is given as A, but since the reaction and options are not visible, I cannot independently verify whether A is actually correct.