The opening price of China Futures Exchange is generated through call auction. The opening price of call auction should be made within 5 minutes after the opening of a certain variety of contract in a certain month of each trading day. Among them, the first 4 minutes are the reporting time of the buying price and selling price of the futures contract, and the last 1 minute is the call auction matchmaking time, and the opening price will be generated when the market opens. The trading system automatically controls the start and end of call auction declaration and displays it on the computer terminal. Therefore, this question chooses C.