老师，此类题如何推导，总是找不到思路？

问题如下：

Which of the following combinations replicates a long derivative position?

选项：

A.

A short derivative and a long asset

B.

A long asset and a short risk-free bond

C.

A short derivative and a short risk-free bond

解释：

B is correct. A long asset and a short risk-free asset (meaning to borrow at the risk-free rate) can be combined to produce a long derivative position.

A is incorrect because a short derivative and a long asset combine to produce a position equivalent to a long risk-free bond, not a long derivative.

C is incorrect because a short derivative and a short risk-free bond combine to produce a position equivalent to a short asset, not a long derivative.