Q4) [6 marks] The graph of f'(x) is shown below. D A C E B a) Write down the letter(s) that corresponds to the x-coordinate of the local maximum of f (x). b) Write down the letter(s) that corresponds to the x-coordinate of the point of inflection of f (x). c) Write down the interval for which f(x) is concave up. d) Sketch f(x) in the grid provided above (clearly showing extrema and points of inflection)