1.    How to create a bull spread ？
　　A.     Buy a put with a strike price of X= 55, and sell a put with a strike price of 50.
　　B.     Buy  a put with a strike price of X = 50, and sell a put with a strike price of 55.
　　C.     Buy a call with a premium of 5, and sell a call with a premium of 7
　　D.     Buy a call with a strike price of X = 50, and sell a put with a strike price of 55.
　　Answer: B
　　A bull spread involves buying a put with a low strike price and selling another put with a high strike price or buying a call with a low strike price and selling another call with a high strike price.