A uniformly charged semicircular arc of radius $R$ lies above the $x$-axis and is centered at the origin. Its total charge is $Q$. Select the integral setup that gives the potential at the center.

$V=k\int \frac{dq}{R^2}$

$V=k\int Rdq$

$V=k\int \frac{dq\cos \theta }{R}$

$V=k\int \frac{dq}{R}$