Two identical long conducting wires $AOB$ and $COD$ are placed at right angle to each other, with one above other such that ‘ $O$ ’ is their common point for the two. The wires carry $I_1$ and $I_2$ currents, respectively. Point ‘ $I$ ’ is lying at distance ‘ $d$ ’ from ‘ $O$ ’ along a direction perpendicular to the plane containing the wires. The magnetic field at the point ‘ $P$ ’ will be:

• A

  $\frac{{\mu }_0}{2\pi d}\left(\frac{I_1}{I_2}\right)$
• B

  $\frac{{\mu }_0}{2\pi d}\left(I_1+I_2\right)$
• C

  $\frac{{\mu }_0}{2\pi d}\left(I_1^2-I_2^2\right)$
• Correct answer
  D

  $\frac{{\mu }_0}{2\pi d}{\left(I_1^2+I_2^2\right)}^{1/2}$

Hence, the correct answer is option: 'D'.