The teacher writes a one-digit number first on the whiteboard, then writes the largest single digit to its right, and at last, adds $$38$$ to the number. The teacher gets a sum of $$117$$. Which one-digit number did the teacher write at first on the whiteboard? 
选项为:A:$$5$$  B:$$8$$  C:$$9$$  D:$$7$$  E:$$6$$  请回答其中一个选项.