Which two compounds are isomers of each other?
(1) CH3CH2COOH and CH3COOCH2CH3
(2) CH3CH2CHO and CH3COCH3
(3) CH3CHBrCH3 and CH2BrCHBrCH3
(4) CH3CHOHCH3 and CH3CHOHCH2OH
(1) CH3CH2COOH and CH3COOCH2CH3
(2) CH3CH2CHO and CH3COCH3
(3) CH3CHBrCH3 and CH2BrCHBrCH3
(4) CH3CHOHCH3 and CH3CHOHCH2OH