问题如下：
4.What are the correct spot value (S) and the risk-free rate (r) that Lee should use as inputs for the Black model?
选项：
A. 186.73 and 0.39%, respectively
B. 186.73 and 2.20%, respectively
C. 187.95 and 2.20%, respectively
解释：
A is correct
Black’s model to value a call option on a futures contract is c = e-rT[F0(T)N(d1) - XN(d2)]. The underlying F0 is the futures price (186.73). The correct discount rate is the risk-free rate, r = 0.39%.
black option什么时候考虑分红？有divdend yield为什么折现时不考虑？