Assume put options on a stock with strike prices $18 and $20 cost $2 and $3.50, respectively. The two options can be used to create a bull spread if an investor buys the _(a)_ ($18 put or $20 put) and sell the _(b)_ ($18 put or $20 put). This strategy gives rise to an initial cash _(C)__(inflow or outflow) of $_(d)__ Payoff (e) Stock Price St 220 18