This question is built on drawn structures, so the options cannot be reproduced as text. The chemistry it tests is set out below.

An allylic acetate with a palladium(0) catalyst and a soft nucleophile is the Tsuji-Trost allylic substitution, and the interesting part is the regiochemistry.

Pd(0) coordinates the alkene and then ionises the C-OAc bond, expelling acetate and forming a cationic π-allyl palladium complex. That is the crucial intermediate: the positive charge and the palladium are delocalised across all three allylic carbons, so the two termini become equivalent in the sense that either can be attacked.

Benzyl thiol, deprotonated or acting directly, provides a soft, stabilised sulphur nucleophile. Soft nucleophiles attack the π-allyl ligand directly at a terminal carbon, on the face opposite palladium, rather than adding first to the metal.

The consequence is that the S-Bn group may appear at either end of the original allyl unit, and with an unsymmetrical substrate the product is usually the one from attack at the less hindered terminus. The double bond correspondingly shifts position — so the product is often the allylic transposition isomer rather than simple displacement at the carbon that bore the acetate.

Because ionisation and nucleophilic attack each occur with inversion, the overall stereochemical outcome at carbon is net retention for soft nucleophiles.

The mild conditions — 5 mol% catalyst, 23°C, neutral THF — are typical, since the acetate leaves only with palladium's assistance.

Per the official final answer key the answer is option (B).