The graph of f attains local extrema at the same points that f' = 0. There's evidence of this at x = 0 and between x = 3 and x = 3.5. (At both points, curve A attains a maximum, while curve B crosses the x-axis.)
Similarly, the graph of f' attains local extrema at the same points that f'' = 0. This is seen between x = 1.5 and x = 2. (B has a max, C crosses axis)
Also, the graph of A is continuous at x = 1.5 but exhibits a sharp turn, so at this point f is not differentiable and the graph of f' (and subsequently f'') is not continuous.
