In the following reaction the major product [X] is

To determine the major product [X] of the given reaction, let's analyze the reaction conditions and the structural transformation involved:

The starting compound is a sulfoxide, which can undergo a thermal syn-elimination in the presence of acetic anhydride (Ac2O) and sodium acetate (NaOAc). This reaction typically results in the formation of a double bond, effectively removing the sulfoxide group through syn-elimination.
Given these reaction conditions, the major product [X] will be an alkene. Specifically, the syn-elimination of the SO group from the sulfoxide will lead to the formation of cyclohexene.
The following image represents the correct structure of the major product [X]:

Conclusion: The major product formed in this reaction is cyclohexene, and the correct answer is represented by the above image.
The major product formed in the following reaction sequence is
The major product formed in the following reaction sequence is
The major products X and Y in the following reaction sequence are 
The following conversion is an example of

The major product formed in the reaction given below is
