Find the intervals on which f is increasing and the intervals on which it is decreasing. f(x) = 2cos (x) x on [0.21:] Select the correct choice below and, if necessary, ll in the answer box(es) to complete your choice. O A- The function is increasing on the open interva|(s) . The function is never decreasing. (Simplify your answers. Use a comma to separate answers as needed. Type your answers in interval notation. Type an exact answer, using 1: as needed. Use integers or fractions for any numbers in the expression.) O B- The function is increasing on the open interva|(s) and decreasing on the open interval(s) (Simplify your answers. Use a comma to separate answers as needed. Type your answers in interval notation. Type an exact answer, using n: as needed. Use integers or fractions for any numbers in the expression.) O C- The function is decreasing on the open interval(s} . The function is never increasing. (Simplify your answer. Use a comma to separate answers as needed. Type your answers in interval notation. Type an exact answer, using 1: as needed. Use integers or fractions for any numbers in the expression.) O D. The function is never increasing or decreasing