Box contains one counter, and boxes and each contain two counters.
Three counters are removed, one at a time. Before each removal, one of the boxes that is not empty is chosen at random, with each nonempty box equally likely to be chosen. One counter is then removed from that box and is not replaced.
Given that the two counters remaining after the three removals are in the same box, what is the probability that the first counter removed came from box ?
A
B
C
D
E