To determine the domain of the function \( g(x) = -\sqrt{x} + 3 + 5 \), we first simplify the function:
\[ g(x) = -\sqrt{x} + 8 \]
The expression \(-\sqrt{x}\) is only defined for non-negative \(x\), meaning \(x\) needs to be greater than or equal to 0:
\[ x \geq 0 \]
Therefore, the domain of \(g(x)\) is:
\[ [0, \infty) \]
In interval notation, this is written as \(0 \leq x < \infty\).
So, the correct response is \(0 \leq x < \infty\).