Find the Derivative of the Function $f ( x ) = \frac { 1 } { 3 x ^ { 2 } }$

Multiple Choice

Find the derivative of the function. $f ( x ) = \frac { 1 } { 3 x ^ { 2 } }$

A) $2 x - 3$
B) $- \frac { 2 } { 3 x ^ { 3 } }$
C) $\frac { 6 } { x ^ { 3 } }$
D) $2 x + 3$
E) $\frac { 1 } { 3 }$