Let $f ( x ) = 3 ^ { - x } \sinh x$

Multiple Choice

Let $f ( x ) = 3 ^ { - x } \sinh x$ Then $f ^ { \prime } ( x )$ is

A) $3 ^ { - x } [ \cosh x - \ln 3 \sinh x ]$
B) $3 ^ { - x } [ \sinh x - \cosh x ]$
C) $3 ^ { - x } [ \ln 3 \sinh x - \cosh x ]$
D) $3 ^ { - x } [ \sinh x + \cosh x ]$
E) $3 ^ { - x } [ \sinh x + \ln 3 \cosh x ]$