In the binomial tree model, the price of a European call option is computed by multiplying the option payoff at maturity with the actual probabilites and discounting at the risk-adjusted rate multiplying the option payoff at maturity with the risk-adjusted probabilites and discounting at the riskfree rate multiplying the option payoff at maturity with the risk-adjusted probabilites and discounting at the risk-adjusted rate multiplying the option payoff at maturity with the actual probabilites and discounting at the riskfree rate