Q74. Let $f ( x ) = x ^ { 5 } + 2 \mathrm { e } ^ { x / 4 }$ for all $x \in \mathbf { R }$. Consider a function $g ( x )$ such that $( g \circ f ) ( x ) = x$ for all $x \in \mathbf { R }$. Then the value of $8 g ^ { \prime } ( 2 )$ is :\\
(1) 2\\
(2) 8\\
(3) 4\\
(4) 16