Alex is $8$ years older than her two sisters who are twins. The sum of the ages of all three girls is $32$ years old. How old is Alex? ($2007$ Math Kangaroo Problem, Level $5$-$6$, Question \#$9$) 
选项为:A:$$12$$  B:$$18$$  C:$$16$$  D:$$20$$  E:$$14$$  请回答其中一个选项.