$$100$$ squares are placed in a row, each filled up with a digit among $$0$$, $$1$$, $$2$$, $$\cdots $$, $$9$$. Now if a digit appears $$5$$ times or more, all the squares filled up with that digit will be painted red. Find the smallest possible number of red squares. 
选项为:A:$$60$$  B:$$64$$  C:$$68$$  D:$$72$$  E:None of the above  请回答其中一个选项.