12.2.31 Question Help Find the open intervals on which the function is concave upward or concave downward, and find the location of any points of inflection. f(x) = -x# +8x + 30x2+ 12x -5 Select the correct choice below and fill in any answer boxes within your choice. (Type your answer in interval notation.) O A. The function is concave upward on and concave downward on (Use a comma to separate answers as needed.) O B. The function is concave upward on O C. The function is concave downward on