Determine the intervals on which the following function is concave up or concave down Identify any inflection points f(x) = -x-3) Determine the intervals on which the following functions are concave up or concave down. Select the correct choice below and it in the answer box(en) to complete your choice. (Simplify your answer. Type your answer in interval notation. Use a comma to separate answers as needed.) OA. The function is concave up on and concave down on OB. The function is concave down on OC. The function is concave up on