Each of $$100$$ participants of a mathematical competition received four problems to solve. The first question was solved by $$90$$ of the participants, the second by $$85$$, the third by $$80$$, and the fourth by $$70$$. From this information we can deduce that the number of participants who solved all four questions is at least:． 
选项为:A:$$10$$  B:$$15$$  C:$$20$$  D:$$25$$  E:$$70$$  请回答其中一个选项.