Find the intervals on which f is increasing and the intervals on which it is decreasing f x 12x5 105x4 240x Find f x f x Select the correct choice below and if necessary fill in the answer box es to complete your choice OA The function is increasing on the open interval s and decreasing on the open interval s Simplify your answers Type your answers in interval notation Use a comma to separate answers as needed B The function is decreasing on the open interval s increasing Simplify your answer Type your answer in interval notation Use a comma to separate answers as needed The function is never C The function is increasing on the open interval s The function is never decreasing Simplify your answer Type your answer in interval notation Use a comma to separate answers as needed D The function is never increasing or decreasing