Two concentric coils of 10 turns each are situated in the same plane. their radii are $20\;cm$ and $40\;cm$ , they carry $0.2\;A$ and $0.3\;a$ current respectively in opposite directions, the magnetic field(in tesla) at the centre is

Question

$\begin{array}{1 1} \large\frac{35 \mu_0}{4} \\ \large\frac{\mu_0}{80} \\ \large\frac{7 \mu_0}{80} \\ \large\frac{5 \mu_0}{4} \end{array}$