Two identical conducting wires AOB and COD are placed at right angles to each other. The wire AOB carries an electric current $I_1$ and COD carries a current $I_2$. The magnetic field on a point lying at a distance d from O, in a direction perpendicular to the plane of the wires AOB and COD, will be given by :

Question

( A ) $\frac{\mu_0}{2 \pi} (\frac{I_1 + I_2}{d})^{1/2}$
( B ) $\frac{\mu_0}{2 \pi d} (I_1^2 + I_2^2)$
( C ) $\frac{\mu_0}{2 \pi d} (I_1^2 + I_2^2)^{1/2}$
( D ) $\frac{\mu_0}{2 \pi d} (I_1 + I_2)$