Which compound reacts to form a ketone when warmed with an acidified solution of potassium dichromate(VI)?
CH3CH2CH2CH2OH\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{OH}CH3CH2CH2CH2OH
CH3CH(OH)CH2CH3\text{CH}_3\text{CH(OH)CH}_2\text{CH}_3CH3CH(OH)CH2CH3
(CH3)3COH(\text{CH}_3)_3\text{COH}(CH3)3COH
CH3CH2CH2CHO\text{CH}_3\text{CH}_2\text{CH}_2\text{CHO}CH3CH2CH2CHO