3) An investor buys a European call option with a strike price of K and maturity T and sells a put with the same strike price and maturity. The payoff to the investor is:

a) max (X-ST, 0) + max (ST-X, 0) b) max (X-ST, 0) - max (ST-X, 0) c) 0 d) - max (X-ST, 0) + max (ST-X, 0) e) - max (X-ST, 0) - max (ST-X, 0)