Find any critical numbers for the function f(x) =7x -3x2+5 and then use the second derivative test to decide whether the critical numbers lead to relative maxima or relative minima. If the second derivative test gives no information, use the first derivative test instead. Select the correct choice below and fill in any answer boxes within your choice. O A. The critical number(s) of f(x) is/are x = (Use a comma to separate answers as needed.) O B. There are no critical numbers. There is a relative at the smaller critical number. There is a relative at the larger critical number