Schemes 1 and 2 describe sequential transformation of alkynes M and N. Consider only the major products formed in each step for both schemes.
The product X is -
This problem can be solved by using the concept of nucleophilic substitution reaction, oxidation and reduction reaction including strength of nucleophile and regioselectivity.
Reaction of Scheme 1 can be completed as
Among two nucleophilic group I and II, II is more nucleophilic and then will react selectively as follows.
Hence, using the concept of regioselectivity we come on the conclusion that final product is correctly represented by structure.