Considering the following reaction sequence, the correct...

Benzene undergoes friedel craft's reaction with succinic anhydride in presence of anhydrous AlCl₃ to form P.The mechanism of the reaction is electrophilic substitution.

The keto group in P gets reduced on reaction Zn/Hg in HCl to form Q that is 4-phenylbutanoic acid.

This reacts with thionyl chloride to form R, that is

4-Phenylbutanoyl chloride.

R again undergoes friedel craft's reaction to form S.

S gets reduced on reaction Zn/Hg in HCl to form a hydrocarbon as given in the reactions below.

Compound $\left(S\right)$ can not decolorizes bromine water.

${R}_{2}Cd$ is a less reactive nucleophile so reaction stops at carbonyl group.

Due to the presence of carbonyl group both P and S forms oxime with hydroxyl amine.