Let \( f(x) = x^5 + 2e^{x/4} \) for all \( x \in \mathbb{R} \). Consider a function \( g(x) \) such that \( (gof)(x) = x \) for all \( x \in \mathbb{R} \). Then the value of \( 8g'(2) \) is:
\( 16 \)
\( 8 \)
\( 2 \)
\( 4 \)