A four-carbon alcohol was oxidized with acidified potassium dichromate to form ketone. Which structure does represent the original alcohol?

$\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$

$\mathrm{H}_{2} \mathrm{C}=\mathrm{CHCH}_{2} \mathrm{CH}_{2} \mathrm{OH}$

$\mathrm{CH}_{3} \mathrm{C}\left(\mathrm{CH}_{3}\right) \mathrm{OHCH}_{3}$

$\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_{3}$