Differentiate $f ( x ) = x e ^ { - 2 x }$

Multiple Choice

Differentiate $f ( x ) = x e ^ { - 2 x }$ .

A) $e ^ { - 2 x } ( 1 - 2 x )$
B) $e ^ { - 2 x } ( 1 - 4 x )$
C) $e ^ { - 2 x } ( 1 + x )$
D) $- 2 e ^ { - 2 x }$