The payoff for the holder of a short position in a forward contract is accurately represented by the equation $K - S_T$. In this equation, $K$ represents the delivery price, which is the price agreed upon at the inception of the contract for the delivery of the underlying asset in the future. $S_T$ represents the spot price of the underlying asset at the time of delivery. The difference between these two prices ($K - S_T$) represents the payoff for the short position holder. If the delivery price is higher than the spot price at the time of delivery ($K > S_T$), the short position holder will make a profit. Conversely, if the spot price at the time of delivery is higher than the delivery price ($S_T > K$), the short position holder will incur a loss. This is because the short position holder is obligated to sell the underlying asset at the delivery price, which could be lower than the current market price.

Choice B is incorrect. The expression $S_T - K$ represents the payoff for a long position in a forward contract, not a short position. In this case, the holder of the contract agrees to buy an asset at a predetermined price ($K$) and would benefit if the spot price at maturity ($S_T$) is higher than this agreed price.

Choice C is incorrect. The expression $\max(0, X - S_T)$ represents the payoff for a long position in a put option, not a short position in a forward contract. Here, $X$ denotes the strike price of the option and $S_T$ denotes the spot price at maturity. If $X > S_T$ (i.e., if it's more profitable to exercise than to sell on market), then profit equals $X - S_T$; otherwise, it's more profitable not to exercise and profit equals 0.

Choice D is incorrect. The expression $\max(0, S_T - X)$ represents the payoff for a long position in a call option rather than that of a short forward contract holder. In this case, if $S_T > X$, then profit equals $S_T - X$; otherwise, it's more profitable not to exercise and profit equals 0.