I would guess A applies in general. For example, if a fair coin is tossed 4 times and it comes up heads each time, it might be judged that the next toss of the coin must be tails by assuming that it's most unlikely that heads would appear yet again; or it could be judged that it must be heads for a different reasoning. Whichever way it is judged, the reasoning is subjective and faulty, because the chances are actually still 1/2 for either heads or tails. So, just as the judgment of the probabilities of heads was faulty, then the result of adding the estimates of probability is likely to be false, too.