A and B together can do a piece of work in 5 days and A alone can do it in 8 days, then B alone can do the same piece of work in :
[A] $16\tfrac{4}{5}days$
[B] $13\tfrac{1}{3}days$
[C] $12\tfrac{3}{5}days$
[D] $11\tfrac{1}{3}days$