Which of the following descriptions of how option payoffs are determined is most accurate()

A. The long position in an interest rate call option receives cash at expiration equal to Max[0, (reference rate-strike rate) ] × notional principal amount. 

B. The payoff on a stock index option is the difference between the index level at expiration and the exercise price. 

C. Payoffs on futures options can be determined without knowing the spot price of the underlying commodity.

用于组织培养中的植物器官或组织，称为（）

A.组织切片

B.原生质体

C.外植体

D.愈伤组织