Find the largest open intervals on which the function is concave upward or concave downward, and find the location of any points of inflection. 5 f(x ) = X - 8 . . . Select the correct choice below and fill in the answer boxes to complete your choice. (Type your answer in interval notation. Use a comma to separate answers as needed. Use integers or fractions for any numbers in the expression.) O A. The function is concave upward on and concave downward on OB. The function is concave downward on There are no intervals on which the function is concave upward. O C. The function is concave upward on There are no intervals on which the function is concave downward