After reading fantastic beasts and where to find them, your professor discovers that unicorns are equally likely to have 0, 1, 2, or 3 offspring. unfortunately, only one unicorn is left. that is, let (zn)∞ n=0 be a branching process that describes the population of unicorns at time n. the offspring distribution is uniformly distributed on {0, 1, 2, 3}, and z0 = 1. (a) find the probability that the population of unicorns will go extinct by the second generation. (b) find the probability that the population of unicorns goes extinct.