Amy picks some numbers as shown below:  $13, 20, 14, 15, 19, 20, 20, 19, 19, 15, 19, 19, 20, 13, 15$.  What is the difference between their mode and median? 
选项为:A:$$0$$  B:$$1$$  C:$$2$$  D:$$19$$  E:$$20$$  请回答其中一个选项.