A bus leaves from a bus stop at $06:30$ and then every half hour afterwards. If ~arrives at the bus stop at $10:32$, how long does he have to wait for a bus? 
选项为:A:$28\rm min$  B:$18\rm min$  C:$32\rm min$  D:$2\rm min$  E:$32\rm min$  请回答其中一个选项.