jee-advanced 2010 Q22
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Let $f$ be a real-valued function defined on the interval $( - 1,1 )$ such that $e ^ { - x } f ( x ) = 2 + \int _ { 0 } ^ { x } \sqrt { t ^ { 4 } + 1 } d t$, for all $x \in ( - 1,1 )$, and let $f ^ { - 1 }$ be the inverse function of $f$. Then $\left( f ^ { - 1 } \right) ^ { \prime } ( 2 )$ is equal to
A) 1
B) $\frac { 1 } { 3 }$
C) $\frac { 1 } { 2 }$
D) $\frac { 1 } { e }$