The product formed in the following reaction sequence is :

The given sequence converts an alcohol to its corresponding carboxylic acid by way of a halide and a Grignard reagent. Let us analyse every step.

Step 1 : $$SOCl_2$$ on an alcohol
Thionyl chloride replaces the $$-OH$$ group by $$-Cl$$ through the $$S_{Ni}$$ mechanism with overall retention of configuration.
If the starting material is $$C_6H_5CH_2OH$$ (benzyl alcohol), the product after this step is the benzyl chloride $$C_6H_5CH_2Cl$$.

Step 2 : Formation of the Grignard reagent
$$C_6H_5CH_2Cl \xrightarrow{\,Mg,\; dry\; ether\,} C_6H_5CH_2MgCl$$

Step 3 : Carboxylation
A Grignard reagent adds to dry carbon dioxide to give the magnesium salt of a carboxylic acid, which on hydrolytic work-up furnishes the free acid.
$$C_6H_5CH_2MgCl \;+\; CO_2 \;\longrightarrow\; C_6H_5CH_2COO^{-}Mg^{+}Cl$$
$$C_6H_5CH_2COO^{-}Mg^{+}Cl \xrightarrow{\,H_3O^{+}\,} C_6H_5CH_2COOH$$

The final product therefore is phenylacetic acid, $$C_6H_5CH_2COOH$$.

Among the given alternatives this structure is shown only in Option D.

Hence, the product formed in the reaction sequence is: Option D which is phenylacetic acid, $$C_6H_5CH_2COOH$$.