$ABCDEF$ is a regular hexagon
$\mathrm { K } , \mathrm { L } \in [ \mathrm { AD } ]$
$| \mathrm { AB } | = 6$ units
$| \mathrm { KL } | = \mathrm { x }$
In the figure, points $K$ and $L$ are on semicircles with diameters $AB$ and $DE$ respectively.
Accordingly, what is $x$ in units?
A) 5
B) 6
C) 9
D) $3 \sqrt { 3 }$
E) $6 \sqrt { 3 }$