A football weighs $450\rm g$ and an empty box weighs $1.5\rm kg$.  After some identical footballs are placed inside a box, the box weighs $12.3\rm kg$.  How many footballs are there in the box? 
选项为:A:$$18$$  B:$$22$$  C:$$24$$  D:$$28$$  E:$$20$$  请回答其中一个选项.