Answer
$ (c)$
Work Step by Step
The domain of a rational expression is the whole set of real numbers, excluding the numbers that yield zero in the denominator.
Here, we exclude $x$ for which
denominator = 0
$ x^{3}+x=0\qquad$... factor out x...
$x(x^{2}+1)=0$
By the zero product principle, at least one of the factors is zero.
$x^{2}+1$ is never zero, because $x^{2}\geq 0$.
So, the only number to exclude from the domain is $x=0$.
