4. (A) At present, there are stock calls with A strike price of RMB 60 with A premium of 2.5 points in the market, and those with A strike price of RMB 75 with A premium of 1 point. Xiaohua decides to establish A long call spread strategy and asks how to buy and sell calls in the market. What is Xiao Hua's view of the market for establishing this strategy? (10%). (B) What is the maximum loss of this strategy by taking (A)? What is the maximum profit? What is the break-even point? If the underlying stock price is 70 yuan, what is the profit or loss of Xiaohua? (Value of each point is NT $2,000)