$A$ current loop $ABCD$ is held fixed on the plane of the paper as shown in the figure. The arcs $BC$ (radius $= b$) and $DA$ (radius $= a$) of the loop are joined by two straight wires $AB$ and $CD$. $A$ steady current $I$ is flowing in the loop. The angle made by $AB$ and $CD$ at the origin $O$ is $30^o$. Another straight thin wire with a steady current $I_1$ flowing out of the plane of the paper is kept at the origin. Due to the presence of the current $I_1$ at the origin:

• A
  The forces on $AB$ and $DC$ are zero.
• B
  The forces on $AD$ and $BC$ are zero.
• C
  The magnitude of the net force on the loop is given by $\frac{I_1 I \mu_0}{4\pi} \left[ 2(b - a) + \frac{\pi}{3}(a + b) \right]$.
• D
  The magnitude of the net force on the loop is given by $\frac{\mu_0 I I_1}{24ab}(b - a)$.