Larger number of oxidation states are exhibited by the actinoids then those by the lanthanoids, the main reason being

Options

A. More reactive nature of the actinides than the lanthanides
B. 4f orbitals more diffused than the 5f orbitals
C. More energy difference between 5f and 6d than between 4f and 5d orbitals
D. lesser energy difference between 5f and 6d than between 4f and 5d orbitals.

Answer

D