The number of ounces of water needed to reduce $$9$$ ounces of shaving lotion containing $$50\textbackslash\%$$ alcohol to a lotion containing $$30\textbackslash\%$$ alcohol is: ($$1953 $$ AHSME Problem, Question \#$$9$$) 
选项为:A:$$3$$  B:$$4$$  C:$$5$$  D:$$6$$  E:$$7$$  请回答其中一个选项.