For the following function, find (a) the critical numbers, (b) the open intervals where the function is increasing, and (c) the open intervals where it is decreasing. f(x)=x+16x+54x+8 (a) Identify the critical numbers of the function. Select the correct choice below and, if necessary, fill in the answer box to complete your choice. OA. The critical number(s) is/are (Type an integer or a simplified fraction. Use a comma to separate answers as needed.) B. There are no critical numbers.