In this fictional "Old Island", all the numbers contain only odd digits. The order of the counting numbers is as follows:  1, 3, 5, 7, $\cdots $ , 19, 31, 33, $\cdots $  What is the 31st counting number in the island? 
选项为:A:$$101$$  B:$$111$$  C:$$99$$  D:$$113$$  E:None of the above.  请回答其中一个选项.