C

Step 1: When acetone (CH₃COCH₃) reacts with phenyl magnesium bromide (C₆H₅MgBr), it undergoes a nucleophilic addition. The Grignard reagent attacks the carbonyl carbon of acetone.
Step 2: This forms an alkoxide intermediate.
Step 3: Upon acidic hydrolysis, the alkoxide is converted to the corresponding alcohol.
The product of the reaction is thus a secondary alcohol, specifically 1-phenyl-2-propanol, which corresponds to Option C.
Therefore, C is the correct answer.