Four hypothetical binary mixtures are given below with their boiling points (bp). Which of them can be separated by simple distillation?

$\left(\mathrm{a}\right)$ $\mathrm{A} \left(\mathrm{bp}=78°\mathrm{C}\right)+\mathrm{B} \left(\mathrm{bp}=85°\mathrm{C}\right)$

$\left(\mathrm{b}\right)$ $\mathrm{A} \left(\mathrm{bp}=78°\mathrm{C}\right)+\mathrm{B} \left(\mathrm{bp}=90°\mathrm{C}\right)$

$\left(\mathrm{c}\right)$ $\mathrm{A} \left(\mathrm{bp}=78°\mathrm{C}\right)+\mathrm{C} \left(\mathrm{bp}=20°\mathrm{C}\right)$

$\left(\mathrm{d}\right)$ $\mathrm{A} \left(\mathrm{bp}=78°\mathrm{C}\right)+\mathrm{D} \left(\mathrm{bp}=130°\mathrm{C}\right)$