Estimate by testing perfect cubes:

• $2^3 = 8$
• $3^3 = 27$
• $4^3 = 64$

Since $27 < 30 < 64$, we know $3 < \sqrt[3]{30} < 4$.

$30$ is much closer to $27$ than to $64$, so $\sqrt[3]{30}$ is closer to $3$ than to $4$.

More precisely: $\sqrt[3]{30} \approx 3.107$

Among the options $\{6, 5, 4, 3\}$, the value $3$ is closest.