Please answer all 3 questions

K Find the intervals on which f(x) is increasing, the intervals on which f(x) is decreasing, and the local extrema. f(x) = -3x -24x-21 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 in interval notation. Type integers or simplified fractions. Use a comma to separate answers as needed.) O B. The function is never increasing