A vanilla call option has a fixed strike price (X) and a payoff that only depends on the expirydate share price (ST). To be specific, the vanilla call option payoff is max(0, ST - X). In contrast, a fixed lookback call option also has a fixed strike price (X). However, path dependency is introduced because the payoff is a function of the maximum share price achieved over the life of the option. To be specific, the payoff is max(0, Smax - X). Consider a stock with a current price of $60. The volatility () of the share returns is 50% pa and the riskfree interest rate is 6% pa. A fixed lookback call option is written on this stock. The option as a strike price of $45 and one year to expiry. Required : Use a four-step Binomial tree and risk-neutral valuation to calculate an approximate value for this fixed lookback call option. note: on each path, when assessing the maximum share price along that path, we will not consider the starting share price of $60. In other words, only consider the four share price that come after the $60.