The actinoids exhibit more number of oxidation states in general than the lanthanoids. This is because :

Question

( A ) the 5f orbitals extend further from the nucleus than the 4f orbitals
( B ) the 5f orbitals are more buried than the 4f orbitals
( C ) the actinoids are more reactive than the lanthanoids
( D ) there is a similarity between 4f and 5f orbitals in their angular part of the wave function