Answer the following questions about the function whose derivative is given below. K a. What are the critical points of f? b. On what open intervals is f increasing or decreasing? c. At what points, if any, does f assume local maximum or minimum values? f' (x) - (8 sin x -8) (2 cos x + 13 , Osx=2n OB. The function f is increasing on the open interval(s) 6 6 and decreasing on the open interval(s) 6 (Use a comma to separate answers as needed. Type your answers in interval notation. Simplify your answers. Type exact answers, using it as needed. Use integers or fractions for any numbers in the expressions.) O C. The function f is decreasing on the open interval(s) and never increasing. (Use a comma to separate answers as needed. Type your answer in interval notation. Simplify your answer. Type an exact answer, using it as needed. Use integers or fractions for any numbers in the expression.)