Find the Point(s) on the Graph Of $f$ Where the Tangent Line Is Horizontal

Multiple Choice

Find the point(s) on the graph of $f$ where the tangent line is horizontal.
$f ( x ) = x ^ { 2 } e ^ { - x }$

A) $( 0,0 ) , \left( 2 , \frac { 2 ^ { 2 } } { e ^ { 2 } } \right)$
B) $\left( 1 , \frac { 1 } { e } \right)$
C) $( 0,0 )$
D) $\left( 2 , \frac { 2 ^ { 2 } } { e ^ { 2 } } \right)$