An urn A contains 6 white balls and 7 black balls. And urn B contains 8 white balls and 6 black balls. A person draws a ball at random from one of the two urns. It turns out to be black. What is probability that the ball was drawn from urn A?
(A) 7/14
(B) 49/88
(C) 39/88
(D) None of the above