Following figures show the arrangement of bar magnets in different...

$\left(a\right)$ ${M}_{net} = \sqrt{{m}^{2} + {m}^{2} + 2mmcos {90}^{o}} = \sqrt{2}m$

\left(b\right)$<img src="https://cdn-question-pool.Quantrex.app/pyq/neet/6de0716b-5195-4a6d-aeb4-a5fcddfa2f6c-image.png" style="width: 134px; height: 17px;" />${M}_{net} = m - m = 0$</p><p><br />\left(c\right)$ ${M}_{net} = \sqrt{{m}^{2} + {m}^{2} + 2mmcos {30}^{o}} = m\sqrt{2 + \sqrt{3}}$
\left(d\right)$<img src="https://cdn-question-pool.Quantrex.app/pyq/neet/5e487a4f-e504-4b65-85cd-aae8da8fe2cd-image.png" style="width: 122px; height: 109px;" />${M}_{net} = \sqrt{{m}^{2} + {m}^{2} + 2mmcos {60}^{o}} = \sqrt{3}m$<br />is configuration \left(C\right)\theta$ is least so ${M}_{net}$ is maximum.