Let $f ( x ) = \frac { 1 } { 5 } x ^ { 3 } - \frac { 9 } { 5 } x ^ { 2 } + 3 x$

Multiple Choice

Let $f ( x ) = \frac { 1 } { 5 } x ^ { 3 } - \frac { 9 } { 5 } x ^ { 2 } + 3 x$ Then ƒ has a point of inflection at x =

A) $- \frac { 1 } { 3 }$
B) 1
C) $\frac { 1 } { 3 }$
D) -1
E) 3