Lisa Cox feels that the price of corn is going to rise in the future and wants to lock in a price using either a futures or forward contract. She is unfamiliar with the differences between the two instruments and asks her associate, Matt Kudrow, to explain the differences. Which of Kudrow’s comments is TRUE In futures markets, the role of the clearinghouse is to:()

A. prevent arbitrage and enforce federal regulations. 

B. act as guarantor to both sides of a futures trade. 

C. reduce transaction costs by making contract prices public.

检查泡沫液时主要是检查泡沫液（）。

A、是否超过有效期

B、是否够量

C、是否符合环境要求

D、是否符合防火要求