A - This is the graph of the derivative of the function f(x). Around A f'(x) is changing from negative to positive. That means at A, we have a minimum.

B - At B the derivative is maximum and on the otherhand the second derivative is zero. We have a rising inflection point at B

C - The sign of first derivative changes from positive to negative. Therefore at C we have a maximum.

D - Again we have a similar situation like B. So we have an inflection point at D also. But this is a falling inflection point.

E - At E also we have derivative changing from negative to positive. So we have a minimum at E also.