The B is from the christmas font; at the moment there is a race between the flowering-K and the christmas-A.
The best way is making post for a voting-request to push up the A :o)
Greetings, Bettina
PS: You can see the ranking of the votes when you click on "alphabets" and then "top in 24hours"...
If you are talking about the B that is up today then you can buy it. It is an older font that apparently is brought back by votes. Here is a link