Circles: GRE Math Practice Question#7

 
If the radius of a circle is increased by $1$ unit, the ratio of the new circumference to the new diameter is:

1. $\quad \pi +2$
2. $\quad \dfrac{2\pi+1}{2}$
3. $\quad \pi$
4. $\quad \dfrac{2\pi-1}{2}$
5. $\quad \pi-2$