Components A and B are connected in parallel and this combination is connected in series with component C. All three components work independently. The probabilities that A, B and C work are 0.9, 0.8 and 0.95 respectively. If the system as a whole has failed, what is the probability that component C has failed?
a) 0.63
b) 0.714
c) 0.72
d) 0.28