The addition of Grignard reagent ${\text{CH}}_{\text{3}}\text{MgBr}$ to acetaldehyde is a nucleophilic addition reaction? The electrophile in this reaction is 

Since oxygen has a higher electronegativity than carbon, the carbon-oxygen double bond is polarized. As a result, the carbonyl oxygen is a nucleophilic centre and the carbonyl carbon is an electrophilic one.
Hence, the correct option is option (A) ${\text{CH}}_{\text{3}}\text{CHO}$.