we know that
the volume of a cone is equal to
[tex]V=\frac{1}{3} \pi r^{2}h[/tex]
where
r is the radius of the base of the cone
h is the height of the cone
in this problem we have
[tex]r=x\ units\\h=2x\ units[/tex]
substitute in the formula
[tex]V=\frac{1}{3} \pi x^{2}2x[/tex]
[tex]V=\frac{2}{3} \pi x^{3}\ units^{3}[/tex]
therefore
the answer is the option A
[tex]\frac{2}{3} \pi x^{3}\ units^{3}[/tex]
