AMust have just one turn and would be circular in shape
a
$M=\mathbf{N I} A$
$\mathrm{M}=\mathrm{N} \times \mathrm{I} \times \mathrm{n} \mathrm{R}^{2}$
$\mathrm{M}=\mathrm{N} \times \mathrm{I} \times \mathrm{N} \times \frac{\mathrm{L}^{2}}{4 \mathrm{n}^{2} \mathrm{N}^{2}}$
$\mathrm{L}=\mathrm{N} \times 2 \mathrm{nR}$
$\Rightarrow \mathrm{R}=\frac{\mathrm{L}}{2 \mathrm{nN}} \quad \mathrm{M} \times \frac{1}{\mathrm{N}}$
For $M_{\max } N=1$ and area of circle is maximum