小编导读：高顿网校免费题库，通过针对性地讲解、训练、答疑、模考，对学习过程进行全程跟踪、专家权威解析与指导，帮助考生全面提升备考效果。马上开始练习 >>>
An option trader constructs the following position: buys 1 call with a strike price at X1, buys 1 call with a strike price at X3 and sells 2 calls with a strike X2. Where X1<X2<X3 and X2=1/2×(X1+X3). Which of the following is referred to as this trader';s strategy?
　　A.Butterfly Spread.
　　B.Bull Spread.
　　C.Strap Spread.
　　D.Strip Spread.
　　Answer: A
　　Explanation: Buying a call at a low exercise price, buying another at a higher exercise price, and selling calls with exercise prices between the high and low is called a butterfly spread.