请问一下老师，我觉得最多会带来3的收益呀 根据bull put 的图

问题如下：

Suppose that put options on an asset with strike prices USD 30 and USD 35 and the same time to maturity cost USD 4 and USD 7 (respectively). How can these options be used to create (a) a bear spread and (b) a bull spread?

选项：

解释：

(a) A bear spread is created by buying the put option with a strike price of USD 35 and selling the put option with a strike price of USD 30. (b) A bull spread is created by buying the put option with a strike price of USD 30, selling the put option with a strike price of USD 35, and adding the present value of USD 5 to the portfolio.