Answer:
x ≥ 0
Step-by-step explanation:
Given the function f(x) and g(x) defined below:

The composite function f(g(x)) is:
![f(g(x))=3\sqrt[]{x}-1](https://img.qammunity.org/2023/formulas/mathematics/college/t3rwrte8cggoz8fav5bbfr85rv4xn51u2s.png)
The domain of the function is the value at which the value under the square root sign is non-negative.
Therefore:

The first option is correct.