For a European call option X(strike price)=25 and a European call option X=30 on the same stock with the same time to expiration, it is true that, when the 30 call is at or in the money, the pest statement we can make is:（）
A. the value of the 25 call is greater than or equal to the value of the 30 call.
B. the 30 call is worth at least as much as the 25 call.
C. the value of the 25 call is greater than the value of the 30 call.
参考答案：C
解析：
The strongest true statement is that the value of the 25 call is greater than the value of the 30 call. If the 30 call is at or in the money at expiration, the minimum difference in prices is $ 5. Prior to expiration, the difference will likely be something less, since the 25 call has $ 5 more intrinsic value but will likely have less time value.