Assume that IBM stock S is currently 75, the interest rate r = 1%; and that you are short a call option that expires in one year with strike price K = 80. Construct a one step binomial tree with u = 1.1 and d = 0.9: What is the value of IBM stock at S(1; 1): (a) 80; (b) 75; (c) 82.5; (d) 90