Explain how the clearinghouse would record the following:

a. Mr. A buys a September S\&P 500 futures contract from Ms. B for 2,000 on June 20.

b. Mr. D buys a September S\&P 500 futures contract from Mr. E for 2,100 on June 25.

c. Ms. B buys a September S\&P 500 futures from Mr. D for \(\$ 2,200\) on June 28.

d. Mr. E buys a September S\&P 500 futures from Mr. A for \(\$ 2,500\) on July 3 .