Identify the isomer of $C_9{H}_{12}$ that has the ${?}^{1}H$ NMR spectrum shown. Select the single best answer.

p$$

isopropylbenzene

$1,2,3-$trimethylbenzene

$1,2,4-$trimethylbenzene

propylbenzene

$1,3,5-$trimethylbenzene