Answer:
[tex]\large\boxed{B)\ \dfrac{3V}{3.14r^2}}[/tex]
Step-by-step explanation:
[tex]\dfrac{1}{3}\cdot3.14\cdot r^2h=V\\\\\dfrac{3.14}{3}r^2h=V\qquad\text{multiply both sides by 3}\\\\3\!\!\!\!\diagup^1\cdot\dfrac{3.14}{3\!\!\!\!\diagup_1}r^2h=3V\\\\3.14r^2h=3V\qquad\text{divide both sides by}\ 3.14r^2\\\\h=\dfrac{3V}{3.14r^2}[/tex]