Revised SAT Math: Domain of functions

 
Try the following SAT math question for the Revised SAT on domain of functions.

What is the domain of the function $f$, defined as $f(x)=\dfrac{x}{1+x^2}$ ?

1. $\quad x \geq 0 $
2. $\quad -1 \leq x \leq 1$
3. $\quad \textrm{All real numbers}$
4. $\quad \textrm{All real numbers except $-1$}$