For the function below, graph f and f'. Then estimate points at which the tangent line to f is horizontal. If no such point exists, state that fact. X f(x)= x² +225 C f'(x) = (Simplify your answer. Do not factor.) Use a graphing calculator to graph f(x). Choose the correct graph below. O A. O B. O C. O D. Q Q Q Q Q Q [-50,50,10] by [-0.2,0.2,0.05] window. Use a graphing calculator to graph f'(x). Choose the correct graph below. O A. O B. O C. O D. Q Q Q Q Q [-50,50,10] by [-0.07,0.07,0.01] window. Estimate the points at which the tangent line to f(x) is horizontal. Select the correct choice below and, if necessary, fill in any answer boxes to complete your choice. O A. The coordinates of the point or points where the tangent line to f(x) is horizontal are (Type an ordered pair. Type an integer or a fraction. Use a comma to separate answers as needed.) O B. There are no points at which the tangent line to f(x) is horizontal.