The structure of X is:

The molecule contains two functional groups:

• A nitrile group, $$-C\equiv N$$
• An ether group, $$-OCH_3$$

Step (i)

Phenylmagnesium bromide, $$C_6H_5MgBr$$, is a Grignard reagent and acts as a source of the nucleophilic phenyl group, $$C_6H_5^-$$.

Since only $$1.0$$ equivalent of the Grignard reagent is used, it reacts with the more reactive functional group.

The ether group remains unaffected because ethers are inert towards Grignard reagents.

The electrophilic carbon of the nitrile group undergoes nucleophilic attack by $$C_6H_5^-$$ to form an imine magnesium salt.

$$R-C\equiv N \xrightarrow{C_6H_5MgBr} R-C(C_6H_5)=NMgBr$$

Step (ii)

On acidic hydrolysis, the imine magnesium salt is converted into a ketone.

$$R-C(C_6H_5)=NMgBr \xrightarrow{H_3O^+} R-COC_6H_5$$

Thus, the nitrile group is converted into a phenyl ketone, while the ether group remains unchanged.

Therefore, the major product $$X$$ is the structure containing the group

$$-COC_6H_5$$

with the $$-CH(CH_3)OCH_3$$ group unchanged.

Hence, the correct answer is Option (D).