问题如下：
A plain vanilla interest rate swap is also known as:
选项：
A. a basis swap.
B. a fixed- for- floating swap.
C. an overnight indexed swap.
解释：
B is correct. A plain vanilla swap is a fixed- for- floating interest rate swap, which is the most common type of swap. A is incorrect because a basis swap is a transaction based on the TED spread (T- bills versus Eurodollars) and is not the same as a plain vanilla swap. C is incorrect because an overnight indexed swap is a swap that is tied to a federal funds type of rate, reflecting the rate at which banks borrow overnight, and is not the same as a plain vanilla swap.
请问plain vanilla int rate swap到底是什么？讲义哪里提到过，和Libor有什么关系呢？
