In the Avengers League, there are $25$ superheroes. Six of the superheroes from the galaxy guard left. How many heroes are left?~(adapted from $$2007$$ Math kangaroo Problems, Level $$1-2$$, Question \#$$6$$) 
选项为:A:$$19$$  B:$$23$$  C:$$24$$  D:$$25$$  E:$$20$$  请回答其中一个选项.