Please answer the following question.

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) =x4+ 16x3+64x2 + 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. O A. The critical number(s) is/are (Type an integer or a simplified fraction. Use a comma to separate answers as needed.) O B. There are no critical numbers. (b) Identify the open intervals where the function is increasing. Select the correct choice below and, if necessary, fill in the answer box to complete your choice. O A. The function is increasing on the interval(s) (Type your answer in interval notation. Simplify your answer. Use integers or fractions for any numbers in the expression. Use a comma to separate answers as needed.) O B. There are no intervals where the function is increasing. (c) Identify the open intervals where the function is decreasing. Select the correct choice below and, if necessary, fill in the answer box to complete your choice. O A. The function is decreasing on the interval(s) (Type your answer in interval notation. Simplify your answer. Use integers or fractions for any numbers in the expression. Use a comma to separate answers as needed.) O B. There are no intervals where the function is decreasing