Find the x-values of all points where the function has any relative extrema. Find the value(s) of any relative extrema. f(x)=x+3x-9x+1 Select the correct choice below and, if necessary, fill in any answer boxes within your choice. OA. There are no relative maxima. The function has a relative minimum of at x= (Use a comma to separate answers as needed.) OB. The function has a relative maximum of at x= and a relative minimum of (Use a comma to separate answers as needed.) OC. There are no relative minima. The function has a relative maximum of at x = (Use a comma to separate answers as needed.) OD. There are no relative extrema. at x=