A $$3$$-digit code is needed to open a safe. How many possible codes are there if it is known that only three numbers, $$1$$, $$3$$, and $$5$$, are used in this code, and each of them is used only once? 
选项为:A:$$2$$  B:$$3$$  C:$$4$$  D:$$5$$  E:$$6$$  请回答其中一个选项.