The OptionsBS function in FinTools XL utilizes the Black-Scholes model to calculate the theoretical price and risk sensitivities of European options. Model: This parameter specifies which variant of the Black-Scholes model to use: 1 = Standard Black-Scholes for European options. 2 = Black model for futures options. 3 = Garman-Kohlhagen model for options on foreign currencies. 4 = Extended Black-Scholes model for options with dividends. TypeOpt: Determines the type of the option: C or 1 = Call option. P or 2 = Put option. Func: Specifies the desired output from the function: 1 = Theoretical price of the option. 2 = Delta, measures the rate of change of the option's price per unit change in the underlying asset's price. 3 = Gamma, measures the rate of change in delta per unit change in the underlying asset's price. 4 = Theta, measures the sensitivity of the option's price to the passage of time. 5 = Vega, measures sensitivity of the option's price to changes in volatility of the underlying asset. 6 = Rho, measures sensitivity of the option's price to changes in the interest rate. Underlying (S): The current price of the underlying asset. Exercise (X): The strike price of the option. Time (T): The time to expiration of the option, usually expressed in years. Volatility (σ): The annualized standard deviation of the underlying asset's returns, expressed as a decimal. Interest Rate (r): The risk-free interest rate, expressed as a decimal, applicable over the life of the option. Dividend Yield (q): The annual dividend yield of the underlying asset, expressed as a decimal. For stocks that do not pay dividends, this would be zero. MarketOptionPrice: Used when calculating implied volatility, it is the current market price of the option. Each of these inputs plays a crucial role in determining the output of the OptionsBS function, whether that be the theoretical price of the option or one of its Greek sensitivities. This model assumes that the price changes of the underlying asset are log-normally distributed and that there are no arbitrage opportunities.