Revised SAT Math: Manipulating function expressions

 
Try the following SAT math question that deals with manipulating function expressions.

If $f(x)=x^2-x-1$, then $f(x+h)-f(x)$ equals

1. $\quad h^2 – h$
2. $\quad h(2x+h-1)$
3. $\quad 2xh-x-1$
4. $\quad 2xh+x-1$