The pair in which both actinides show +3 oxidation state only is

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Correct option is A

​The 14 elements from thorium (Th, Z=90, 5f¹) to lawrencium (Lr, Z=103, 5f¹⁴) involve the progressive completion of the 5f subshell. Whereas, like the lanthanoids, a common oxidation state of the actinoids is An(III), unlike the lanthanoids the early members of the series occur in a rich variety of other oxidation states. The Frost diagrams in figure show that oxidation numbers higher than +3 are easily accessible and often preferred for the early elements of the block (Th, Pa, U, Np, Pu) whereas +3 becomes predominant in Am and beyond. Unlike in the lanthanoids, the f orbitals of the early actinoids extend into the bonding region, so the spectra of their complexes are strongly affected by ligands. The 5f and 6d orbitals are less compact than the 4f and 5d orbitals and the electrons in them are more available for bonding. Thus the outermost electron configuration of U is 5f³6d¹7s² with all six electrons available for bonding. At around Am and Cm the 5f and 6d orbital energies are lower due to their poor screening by the other electrons, so that the later actinoids behave like the lanthanoids with only the outermost three electrons being readily ionized.

Electronic configuration of actinium (Ac) is [Rn] 6d¹7s².

Electronic configuration of lawrencium (Lr) is [Rn] 5f¹⁴7s²7p¹

Electronic configuration of nobelium (No) is [Rn] 5f¹⁴7s²​

Electronic configuration of curium (Cm) is [Rn] 5f⁷6d¹7s²​

Electronic configuration of berkelium (Bk) is [Rn] 5f⁹7s²​