A circular coil of wire consisting of 100 turns, each of radius `8.0 cm` carries a current of `0.40 A`. What is the magnitude of the magnetic field B at the centre of the coil?
Options:
(a) `pi xx10^(-3) T`
(b) `2pi xx10^(-4) T`
(c) `pi xx10^(-4) T`
(d) Zero