Wires $1$ and $2$ carrying currents $i_1$ and $i_2$ respectively are inclined at an angle $\theta$ to each other. What is the force on a small element $dl$ of wire $2$ at a distance of $r$ from wire $1$ (as shown in figure) due to the magnetic field of wire $1$?

• A
  $\frac{\mu_0}{2\pi r} i_1 i_2 \, dl \tan \theta$
• B
  $\frac{\mu_0}{2\pi r} i_1 i_2 \, dl \sin \theta$
• C
  $\frac{\mu_0}{2\pi r} i_1 i_2 \, dl \cos \theta$
• D
  $\frac{\mu_0}{4\pi r} i_1 i_2 \, dl \sin \theta$