On meter length of wires carriers a constant current. The wire is bent to from a circular loop. The magnetic field at the centre of this loop is `B`. The same is now bent to form a circular loop of smaller radius to have four turns in the loop. The magnetic field at the centre of this loop `B`. The same is now bent to form a circular loop of smaller radius of have four turns in the loop. The magnetic field at the centre of this new loop is
A. `B/2`
B. `4B`
C. `B/4`
D. `16B`
