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

$\mathrm {CH_3CH_2CH_2OH}$

$\mathrm {H_2C = CHCH_2CH_2OH}$

$\mathrm {CH_3C(CH_3)OHCH_3}$

$\mathrm {CH_3CH_2CH(OH)CH_3}$