First you want the value of g to be greater than g'. Remember that g' is the slope. At point E note that the value of g is as negative as it can get, and the slope is zero, so g < g' and this can't be the right answer. Hint: find a point where g is positive, g' is 0 and g'' is negative. To determine whether g'' is positive or negative consider how the slope is changing nearby. For example at C the slope looks pretty constant - therefore g'' is close to 0, and at E the slope is quickly changing from negative to psoitive, so g'' is positive. Hope this helps!