Correct option (C) (II) > (I) > (III)
Explanation:
Nucleophile attacks the most electrophilic site first. Among aldehyde and a ketone, aldehydes are more electrophilic as in ketones the δ+ charge an carbonyl carbon is decreased by +I effect of both alkyl groups.
More over in the tetrahedral intermediate aldehydes have less steric repulsion than ketone and aldehydes increases the –ve charge on oxygen less in comparison to ketones.
Based on the above the order of reactivity is (II) > (I) > (III)
