Answer:
Option 4
Step-by-step explanation:
h = x units
diameter = x units
r = (x/2) units
[tex]\sf \boxed{\text{ \bf Volume of cone = $\dfrac{1}{3} \pi r^2h$}}[/tex]
[tex]\sf =\dfrac{1}{3}*\pi * (\dfrac{x}{2})^2*x\\\\=\dfrac{1}{3}*\pi*\dfrac{x^2}{4}*x\\\\=\dfrac{1}{12}\pi x^3[/tex]