To solve this problem, we need to understand the reaction between acetone and methylmagnesium chloride, followed by hydrolysis.$\newline$This is an example of a Grignard reaction, which involves the addition of a Grignard reagent to a carbonyl compound.$\newline$Step-by-step mechanism:$\newline$1. Reaction of acetone with methylmagnesium chloride:$\newline$• Acetone is a ketone with the structure $(CH_3)_2C=O. \newline$• Methylmagnesium chloride is a Grignard reagent with the formula $CH_3MgCl. \newline$• The nucleophilic carbon of the Grignard reagent attacks the electrophilic carbon of the carbonyl group in acetone.$\newline$• This results in the formation of an alkoxide intermediate:$\newline (CH_3)_2C=O + CH_3MgCl \rightarrow (CH_3)_3COMgCl \newline$2. Hydrolysis of the alkoxide intermediate:$\newline$• The alkoxide is then hydrolyzed with water to form the corresponding alcohol.$\newline$• The hydrolysis step involves the replacement of the MgCl group with a hydrogen atom.$\newline (CH_3)_3COMgCl + H_2O \rightarrow (CH_3)_3COH + Mg(OH)Cl \newline$The final product is tert-butyl alcohol, which is a tertiary alcohol.$\newline$Analyzing the options:$\newline$• Option 1: Sec. butyl alcohol is incorrect as it is a secondary alcohol.$\newline$• Option 2: Tert. butyl alcohol is correct as it matches the product formed.$\newline$• Option 3: Isobutyl alcohol is incorrect as it is a primary alcohol.$\newline$• Option 4: Isopropyl alcohol is incorrect as it is a secondary alcohol.$\newline$Therefore, the correct option is Option 2: Tert. butyl alcohol.