Fill in the blanks with digits so that the equality is true: $$45\times $$\_$$3=3$$\_ \_ \_. The sum of the four digits placed in the blanks is:． 
选项为:A:equal to $$20$$  B:equal to $$21$$  C:equal to $$17$$  D:more than $$21$$  E:less than $$17$$  请回答其中一个选项.