Find the intervals on which f(x) is increasing and the intervals on which f(x) is decreasing. Then sketch the graph. Add horizontal tangent lines. f(x) =6-12x +6x -x Select the correct choice below and, if necessary, fill in the answer box to complete your choice. O A. The function is increasing on (Type your answer using interval notation. Use a comma to separate answers as needed.) O B. There is no solution. Select the correct choice below and, if necessary, fill in the answer box to complete your choice. O A. The function is decreasing on (Type your answer using interval notation. Use a comma to separate answers as needed.) O B. There is no solution. Choose the correct graph of f(x) =6 - 12x + 6x -x with the correct horizontal tangent line below. OA. O B. O C. O D. O