The reagents A and major product B in the following reaction sequence are

Explanation:-

• The reaction pathway is shown below:

• In the first step of the reaction, piperidine acts as a base and deprotonates H₂S to form a stronger nucleophile SH^-.
• In the next step, the nucleophile SH- undergoes an addition reaction to form followed by reduction with NaBH₄ to form

• In the last step, the generated product undergoes acetal formation with Acetaldehyde (MeCHO) to form the final product.

Conclusion:-

Hence, the reagents A and major product B in the following reaction sequence are A = i. H2S, cat. piperidine; ii. NaBH4 B =