If n is an even positive integer, the double factorial notation n!! represents the product of all the even integers from 2 to n. For example, $8!!=2\cdot4\cdot6\cdot8$. What is the units digit of the following sum?  $2!!+4!!+6!!+\cdot\cdot\cdot+2018!!+2020!!+2022!!$ 
选项为:A:$$0$$  B:$$2$$  C:$$4$$  D:$$6$$  E:$$8$$  请回答其中一个选项.