流动性

问题如下：

Due to their high degree of liquidity and safety, the most common form of collateral for both repo and derivative transactions is:

选项：

A.

shorter-term government securities.

B.

medium-term government securities.

C.

longer-term government securities.

解释：

C is correct. Longer-term government securities are the most common form of collateral for both repo and derivative transactions due to their high degree of liquidity and safety.