Which compound reacts with iodine in the presence of sodium hydroxide to form a yellow precipitate, but does not react with Tollens' reagent to form a silver mirror?
CH3CHO\text{CH}_3\text{CHO}CH3CHO
CH3CH2CHO\text{CH}_3\text{CH}_2\text{CHO}CH3CH2CHO
CH3COCH2CH3\text{CH}_3\text{COCH}_2\text{CH}_3CH3COCH2CH3
CH3CH2COCH2CH3\text{CH}_3\text{CH}_2\text{COCH}_2\text{CH}_3CH3CH2COCH2CH3