human
A certain bottled water operating department has a fixed cost of 200 yuan per day for rent and personnel wages. The cost price of each bottle of water is 5 yuan. When the selling price is 6 yuan, the average daily sales volume is 480 bottles. According to data analysis, for every 1 yuan increase in the selling price on the basis of the cost price, the average daily sales volume decreases by 40 bottles. In order to maximize the average daily sales profit, the selling price should be set at ( )
A. 6.5 yuan B. 8.5 yuan C. 10.5 yuan D. 11.5 yuan
gpt
--- Reasoning ---
1. Is the question multiple-choice question?
Yes

--- Answer ---
grounded