Ans. The loop achieves stable equilibrium when torque $\left( \tau\right) = 0$
As $$ \vec{\tau}=i\left(\vec{A}\times \vec{B} \right)$$
$$ 0=i\left(\vec{A}\times \vec{B} \right) $$
$$\therefore \left(\vec{A}\times \vec{B} \right)=0$$
Which means area vector$ \vec{A}$ must be parallel to magnetic field$ \vec{B}$