A cylindrical conductor of radius $R$ is carrying a constant current. The plot of the magnitude of the magnetic field $B$ with the distance $d$ from the centre of the conductor is correctly represented by the figure:

1.		2.
3.		4.

Two toroids $1$ and $2$ have total no. of turns $200$ and $100$ respectively with average radii $40~\text{cm}$ and $20~\text{cm}$ respectively. If they carry the same current $i,$ what will be the ratio of the magnetic fields along the two loops?
1. $1:1$
2. $4:1$
3. $2:1$
4. $1:2$