increasing: (0, 23,800)
decreasing: (23,800, 50,000)
To obtain maximum profit for popcorn, you should charge the price that yields sales of x = 23,800 bags of popcorn. Since the function changes from increasing to decreasing at x = 23,800, the maximum profit occurs at this value. Therefore, the correct option is a) You should charge the price that yields sales of x = 23,800 bags of popcorn.