老师，没看懂题干和答案。

问题如下：

Explain the argument used for calculating the value of a forward contract.

选项：

解释：

The forward contract is compared to a forward contract with the same maturity that would be entered into today. The present value of the difference between their payoffs can be calculated. We know that the value of a forward contract that would be entered into today is zero and can therefore deduce the value of the other forward contract.