"In multiple step binomial tree s, the delta changes during the life of the option. Hence, the riskless portfolio for each step is different and rebalancing is required to keep the portfolio riskless." O True O False Black-Scholes option pricing model assumes that stock returns has log-normal distribution o True O False It is always optimal to exercise American call options on non-dividend paying stocks as American options give the holder right to exercise anytime during the life option. O True O False