1 0 1 2 3 4 5 6 7 8 1 1. The figure above shows the graph of f', the derivative of the function f on the closed interval 0 S x $ 8. The graph of fr has horizontal tangent lines at x = 2, x = 4, and x = 6. The function f is twice differentiable. Part A: Find the x-coordinate of each of the points of inflection on the graph of f. Give a reason for your answer. Part B: At what value of x does f attain its absolute maximum value on the closed interval 0 S x S 8? Show the analysis that leads to your answer. Part C: For what values of x is the graph of f concave upward? Justify your