The graph above shows the electric field $E$ as a function of $x,$ where $x$ is the distance from a given charge arrangement in an $xyz-$coordinate system. Which of the following could be the arrangement? The graph is a horizontal line. Why is $($E$)$ the correct answer?

$($A$)$ A positive point charge at $x=0$

$($B$)$ Positive charges uniformly distributed inside a sphere with $x=0$ on the sphere's surface

$($C$)$ Positive charges uniformly distributed on the surface of a sphere with $x=0$ on the sphere's surface

$($D$)$ Positive charges uniformly distributed along the $y-$axis

$($E$)$ Positive charges uniformly distributed over the $yz-$plane