Find All Points of Inflection on the Graph of the Function

Multiple Choice

Find all points of inflection on the graph of the function $f ( x ) = \frac { 1 } { 2 } x ^ { 4 } + 2 x ^ { 3 }$

A) $( - 2 , - 8 )$
B) $( 0,0 )$
C) $( 0,0 ) , ( - 4,0 )$
D) $( 0,0 ) ( - 2 , - 8 )$ .
E) $( - 2 , - 8 )$ .