At local minima/maxima of every function their derivative is zero or there is direction change.
Here function \[{\rm{f}}\] is denoted by the curve \[{\rm{c}}\]and it can be seen that when graph \[{\rm{c}}\] has local maxima and minima, black graph has value zero (changing direction).
So, \[{\rm{f(x)}}\] is denoted by curve c light blue curve and \[{\rm{f'(x)}}\] is black curve \[{\rm{b}}\]. We know that \[\frac{{\rm{d}}}{{{\rm{dx}}}}\int_{\rm{a}}^{\rm{x}} {{\rm{f(t)dt = f(x)m}}} \].
So, when the curve of \[\int_{\rm{a}}^{\rm{x}} {{\rm{f(x)dx}}} \] has local maximum and minimum function \[{\rm{f(x)}}\] will be zero.
From the graph it is clear, when curve \[{\rm{a}}\] has maxima or minima the curve c function f \[{\rm{f(x)}}\]has direction change.
Therefore, the curves that represent each function are \[{\rm{f(x)}} \to {\rm{c}}\], \[{\rm{f'(x)}} \to {\rm{b}}\] and \[\int_{\rm{0}}^{\rm{x}} {{\rm{f(t)dt}}} \to {\rm{a}}\].