Each loop or wire in List I carries the same steady current $I$, and lies in one plane. For each, a point $O$ is named. Match each with the size of the magnetic field at $O$ in List II, where $B_0 = \dfrac{\mu_0 I}{4\pi R}$ and $R$ is the same length throughout. List I (P) A circular loop of radius $R$; $O$ is its centre. (Q) A square loop whose sides are each $R$ from its centre $O$. (R) A very long straight wire; $O$ is a point $R$ from it. (S) A loop shaped as an equilateral triangle whose sides are each $R$ from its centre $O$. List II (1) $B_0$; (2) $2B_0$; (3) $3\sqrt3\,B_0$; (4) $4\sqrt2\,B_0$; (5) $2\pi B_0$. Which matching is correct?