6 (option A)
Explanation:x³ = 216
cube root both sides:
[tex]\begin{gathered} \sqrt[3]{x^3}\text{ = }\sqrt[3]{216} \\ x\text{ = }\sqrt[3]{216} \end{gathered}[/tex][tex]\begin{gathered} x\text{ = }\sqrt[3]{(6)^3} \\ x\text{ = 6 (option A)} \end{gathered}[/tex]