Two identical wires A and B, each of length 'l', carry the same current I. Wire A is bent into a circle of radius R and wire B is bent to form a square of side 'a'. If Bₐ and Bᵦ are the values of magnetic field at the centres of the circle and square respectively, then the ratio BA/BB is.
A. ²/8
B. ²/16√2
C. ²/16
D. ²/8√2