Answer
$F^{\prime}(x)=\displaystyle \frac{1}{x}$
Work Step by Step
Use the Second Fundamental Theorem of Calculus (Th 4.11)
$\displaystyle \frac{d}{dx}\left[\int_{a}^{x}f(t)dt\right] =f(x)$
here: a=1, and f(t)$=\displaystyle \frac{1}{t}$
$F^{\prime}(x)=f(x)=\displaystyle \frac{1}{x}$