Four transition metal octahedral complexes, (the choice given below) low spin electron configurations arises only for

In 1 2 3 8 9 d ,d ,d ,d ,d the distribution of electrons in the sets of 2 g t g&e are both for strong ligands and weak ligands field is same. But for 4 5 6 7 d ,d ,d &d there is a difference in the arrangements of electrons in the weak and strong field ligands. A weak ligand will have greater no. of unpaired electrons. Hence, the correct answer is (b).