Our decimal system is base 10 and has digits from 0 to 9
For a 12 base system you have to add two digits. They will be A and B.
So the numbers of three digits that start with B are B01, B02, B03, B04, B05, B06, B07, B08, B09, B0A, B0B, B10, B11, ...
I made a long sequence to help you see more clearly how it works, but you only need to see that the number before and after B0B are B0A and B10.
That is the answer: B0A and B10.