Arrange the following conformational isomers of n-butane in order of their increasing potential energy:

$\mathrm{II}<\mathrm{III}<\mathrm{IV}<\mathrm{I}$

$\mathrm{I}<\mathrm{IV}<\mathrm{III}<\mathrm{II}$

$\mathrm{II}<\mathrm{IV}<\mathrm{III}<\mathrm{I}$

$\mathrm{I}<\mathrm{III}<\mathrm{IV}<\mathrm{II}$