Hint: Volume= side^3
Example:
Side: 3 cm
Volume: 3 x 3 x 3 = 9 cm cubed

Answer:
B. 8
Step-by-step explanation:
We know that Volume = side³. Since we know that the volume is 216, we have to find the cube root of 216, which is 8. 8×8×8 = 216, so 8 is the answer.
Hope this helps!