When a long wire carrying a steady current is bent into a circular coil of one turn, the magnetic induction at its centre is $B$. When the same wire carrying the same current is bent to form a circular coil of $n$ turns of a smaller radius, the magnetic induction at the centre will be
(A) $B / n$
(B) $n B$
(C) $B / n^{2}$
(D) $n^{2} B$