Which of the following are position isomers?

[Step 1]:Compounds having the same molecular formula but different in position of substituents (or) functional group are called position isomers.option (1)  CH3OCH3 and CH3CH2OH are functional isomers.option (2) CH3CH2CH2CH3 and CH3−C|CH3H−CH3are chain isomers.option (3) are position isomers.option (4) CH3−CH=CH−CH3  and  CH2=C|CH3−CH3 not isomers.